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69-644: CMS EXEC , or EXEC , is an interpreted, command procedure control, computer scripting language used by the CMS EXEC Processor supplied with the IBM Virtual Machine / Conversational Monitor System ( VM/CMS ) operating system. EXEC was written in 1966 by Stuart Madnick at MIT on the model of CTSS RUNCOM . He originally called this processor COMMAND, and it was later renamed EXEC. CMS EXEC has been superseded by EXEC 2 and REXX . All three — CMS EXEC, EXEC 2 and REXX — continue to be supported by

138-446: A Perl 4 binary with Oracle Call Interface compiled in. This has however since been replaced by a library (Perl Module), DBD::Oracle . Other complex and task-oriented applications may incorporate and expose an embedded programming language to allow their users more control and give them more functionality than can be available through a user interface, no matter how sophisticated. For example, Autodesk Maya 3D authoring tools embed

207-745: A Windows Script Host engine (VBScript, JScript and VBA by default in Windows and third-party engines including implementations of Rexx, Perl, Tcl, Python, XSLT, Ruby, Modern Pascal, Delphi , and C). A majority of applications can access and use operating system components via the object models or its own functions. Other devices like programmable calculators may also have glue languages; the operating systems of PDAs such as Windows CE may have available native or third-party macro tools that glue applications together, in addition to implementations of common glue languages—including Windows NT , DOS , and some Unix shells , Rexx, Modern Pascal, PHP, and Perl. Depending upon

276-418: A "common" language, the user gets the advantage of being able to transfer skills from application to application. A more generic alternative is simply to provide a library (often a C library) that a general-purpose language can use to control the application, without modifying the language for the specific domain. JavaScript began as and primarily still is a language for scripting inside web browsers ; however,

345-505: A . However, maintaining the validity of this equation means that while the result of a%b is, as expected, in the half-open interval [0, b ), where b is a positive integer, it has to lie in the interval ( b , 0] when b is negative. Python provides a round function for rounding a float to the nearest integer. For tie-breaking , Python 3 uses round to even : round(1.5) and round(2.5) both produce 2 . Versions before 3 used round-away-from-zero : round(0.5)

414-419: A certain type. Python does not support tail call optimization or first-class continuations , and, according to Van Rossum, it never will. However, better support for coroutine -like functionality is provided by extending Python's generators . Before 2.5, generators were lazy iterators ; data was passed unidirectionally out of the generator. From Python 2.5 on, it is possible to pass data back into

483-644: A combination of reference counting and a cycle-detecting garbage collector for memory management . It uses dynamic name resolution ( late binding ), which binds method and variable names during program execution. Its design offers some support for functional programming in the Lisp tradition. It has filter , map and reduce functions; list comprehensions , dictionaries , sets, and generator expressions. The standard library has two modules ( itertools and functools ) that implement functional tools borrowed from Haskell and Standard ML . Its core philosophy

552-420: A decrease in indentation signifies the end of the current block. Thus, the program's visual structure accurately represents its semantic structure. This feature is sometimes termed the off-side rule . Some other languages use indentation this way; but in most, indentation has no semantic meaning. The recommended indent size is four spaces. Python's statements include: The assignment statement ( = ) binds

621-466: A different unofficial Python implementation, PyPy , continues to support Python 2, i.e. "2.7.18+" (plus 3.10), with the plus meaning (at least some) " backported security updates". Python 3.0 was released on 3 December 2008, with some new semantics and changed syntax. At least every Python release since (now unsupported) 3.5 has added some syntax to the language, and a few later releases have dropped outdated modules, or changed semantics, at least in

690-567: A five-member Steering Council to lead the project. Python 2.0 was released on 16 October 2000, with many major new features such as list comprehensions , cycle-detecting garbage collection, reference counting , and Unicode support. Python 2.7's end-of-life was initially set for 2015, then postponed to 2020 out of concern that a large body of existing code could not easily be forward-ported to Python 3. No further security patches or other improvements will be released for it. While Python 2.7 and older versions are officially unsupported,

759-415: A general purpose language or a domain-specific language for a particular environment. When embedded in an application, it may be called an extension language . A scripting language is sometimes referred to as very high-level programming language if it operates at a high level of abstraction, or as a control language , particularly for job control languages on mainframes. The term scripting language

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828-510: A generator function; and from version 3.3, it can be passed through multiple stack levels. Python's expressions include: In Python, a distinction between expressions and statements is rigidly enforced, in contrast to languages such as Common Lisp , Scheme , or Ruby . This leads to duplicating some functionality. For example: Statements cannot be a part of an expression—so list and other comprehensions or lambda expressions , all being expressions, cannot contain statements. A particular case

897-464: A half), followed by 3 years of security support (for same total support as before). Security updates were expedited in 2021 (and again twice in 2022, and more fixed in 2023 and in September 2024 for Python 3.12.6 down to 3.8.20), since all Python versions were insecure (including 2.7 ) because of security issues leading to possible remote code execution and web-cache poisoning . Python 3.10 added

966-474: A language for writing extensions to the browser itself, and several standard embedded languages for controlling the browser, including JavaScript (a dialect of ECMAScript ) or XUL . Scripting languages can be categorized into several different types, with a considerable degree of overlap among the types. Scripting is often contrasted with system programming , as in Ousterhout's dichotomy or " programming in

1035-480: A macro language built into the editor, e.g., The SemWare Editor (TSE), vi improved (VIM), or using an external implementation, e.g., XEDIT , or both, e.g., KEDIT . Sometimes text editors and edit macros are used under the covers to provide other applications, e.g., FILELIST and RDRLIST in CMS . A major class of scripting languages has grown out of the automation of job control , which relates to starting and controlling

1104-445: A matrix‑multiplication operator @ . These operators work like in traditional math; with the same precedence rules , the operators infix ( + and - can also be unary to represent positive and negative numbers respectively). The division between integers produces floating-point results. The behavior of division has changed significantly over time: In Python terms, / is true division (or simply division ), and //

1173-459: A minor way. Since 7 October 2024 , Python 3.13 is the latest stable release, and it and, for few more months, 3.12 are the only releases with active support including for bugfixes (as opposed to just for security) and Python 3.9, is the oldest supported version of Python (albeit in the 'security support' phase), due to Python 3.8 reaching end-of-life . Starting with 3.13, it and later versions have 2 years of full support (up from one and

1242-402: A name as a reference to a separate, dynamically allocated object . Variables may subsequently be rebound at any time to any object. In Python, a variable name is a generic reference holder without a fixed data type ; however, it always refers to some object with a type. This is called dynamic typing —in contrast to statically-typed languages, where each variable may contain only a value of

1311-461: A new and improved interactive interpreter ( REPL ), featuring multi-line editing and color support; an incremental garbage collector (producing shorter pauses for collection in programs with a lot of objects, and addition to the improved speed in 3.11 and 3.12), and an experimental just-in-time (JIT) compiler (such features, can/needs to be enabled specifically for the increase in speed), and an experimental free-threaded build mode, which disables

1380-422: A person in a more manual way. A language that is primarily intended for scripting generally has limited capabilities compared to a general-purpose language. A scripting language may lack the functionality to write complex applications. Typically, a script starts executing at the first line of code whereas an application typically starts at a special point in the code called the entry point . For example, Java

1449-438: A portable and general-purpose language; conversely, a general-purpose language may later develop special domain-specific dialects. Script is a subjective characterization that generally includes the following attributes. A script is usually not compiled – at least not its usual meaning. Generally, they are interpreted directly from source code or from bytecode or run as native after just-in-time compilation . A script

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1518-475: A scripting language for IBM's CP/CMS in 1966. He originally called this processor COMMAND, later named EXEC . Multics included an offshoot of CTSS RUNCOM, also called RUNCOM. EXEC was eventually replaced by EXEC 2 and REXX . Languages such as Tcl and Lua were specifically designed as general-purpose scripting languages that could be embedded in any application. Other languages such as Visual Basic for Applications (VBA) provided strong integration with

1587-447: A single application. A number of languages have been designed for the purpose of replacing application-specific scripting languages by being embeddable in application programs. The application programmer (working in C or another systems language) includes "hooks" where the scripting language can control the application. These languages may be technically equivalent to an application-specific extension language but when an application embeds

1656-402: A specific general-purpose language (e.g. QuakeC , modeled after C), they have custom features that distinguish them. Emacs Lisp , while a fully formed and capable dialect of Lisp , contains many special features that make it most useful for extending the editing functions of Emacs. An application-specific scripting language can be viewed as a domain-specific programming language specialized to

1725-411: A standard format for distributing Python Binaries. Python 3.15 will "Make UTF-8 mode default", the mode exists in all current Python versions, but currently needs to be opted into. UTF-8 is already used, by default, on Windows (and elsewhere), for most things, but e.g. to open files it's not and enabling also makes code fully cross-platform, i.e. use UTF-8 for everything on all platforms. Python

1794-633: A string literal, with no certainty as to which one a programmer should use. Alex Martelli , a Fellow at the Python Software Foundation and Python book author, wrote: "To describe something as 'clever' is not considered a compliment in the Python culture." Python's developers usually strive to avoid premature optimization and reject patches to non-critical parts of the CPython reference implementation that would offer marginal increases in speed at

1863-581: A substantial amount of logic is written in script, it is better characterized as simply another software component, not "glue". Glue languages are especially useful for writing and maintaining: Glue language examples: Macro languages exposed to operating system or application components can serve as glue languages. These include Visual Basic for Applications , WordBasic , LotusScript , CorelScript , Hummingbird Basic, QuickScript, Rexx, SaxBasic , and WinWrap Basic. Other tools like AWK can also be considered glue languages, as can any language implemented by

1932-486: A successor to the ABC programming language and first released it in 1991 as Python 0.9.0. Python 2.0 was released in 2000. Python 3.0, released in 2008, was a major revision not completely backward-compatible with earlier versions. Python 2.7.18, released in 2020, was the last release of Python 2. Python consistently ranks as one of the most popular programming languages, and has gained widespread use in

2001-441: A touch-activated screen. These languages could in principle be used to control any GUI application; but, in practice their use is limited because their use needs support from the application and from the operating system . There are a few exceptions to this limitation. Some GUI scripting languages are based on recognizing graphical objects from their display screen pixels . These GUI scripting languages do not depend on support from

2070-585: Is 1.0 , round(-0.5) is −1.0 . Python allows Boolean expressions with multiple equality relations in a manner that is consistent with general use in mathematics. For example, the expression a < b < c tests whether a is less than b and b is less than c . C-derived languages interpret this expression differently: in C, the expression would first evaluate a < b , resulting in 0 or 1, and that result would then be compared with c . Python uses arbitrary-precision arithmetic for all integer operations. The Decimal type/class in

2139-403: Is floor division. / before version 3.0 is classic division . Rounding towards negative infinity, though different from most languages, adds consistency. For instance, it means that the equation ( a + b ) // b == a // b + 1 is always true. It also means that the equation b * ( a // b ) + a % b == a is valid for both positive and negative values of

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2208-522: Is a multi-paradigm programming language . Object-oriented programming and structured programming are fully supported, and many of their features support functional programming and aspect-oriented programming (including metaprogramming and metaobjects ). Many other paradigms are supported via extensions, including design by contract and logic programming . Python is known as a glue language , able to work very well with many other languages with ease of access. Python uses dynamic typing and

2277-492: Is compiled, and possibly semantics are slightly changed. Python's developers aim for it to be fun to use. This is reflected in its name—a tribute to the British comedy group Monty Python —and in occasionally playful approaches to tutorials and reference materials, such as the use of the terms "spam" and "eggs" (a reference to a Monty Python sketch ) in examples, instead of the often-used "foo" and "bar" . A common neologism in

2346-429: Is generally relatively short and simple. As there is no limit on size or complexity, script is subjective. A few lines of code without branching is probably considered a script. A codebase of multiple files, that performs sophisticated user or hardware interface or complicated algorithms or multiprogramming is probably not considered a script. A script usually automates a task that would otherwise be performed by

2415-532: Is meant to be an easily readable language. Its formatting is visually uncluttered and often uses English keywords where other languages use punctuation. Unlike many other languages, it does not use curly brackets to delimit blocks, and semicolons after statements are allowed but rarely used. It has fewer syntactic exceptions and special cases than C or Pascal . Python uses whitespace indentation, rather than curly brackets or keywords, to delimit blocks . An increase in indentation comes after certain statements;

2484-411: Is not of a suitable type. Despite being dynamically typed , Python is strongly typed , forbidding operations that are not well-defined (for example, adding a number to a string) rather than silently attempting to make sense of them. Python allows programmers to define their own types using classes , most often used for object-oriented programming . New instances of classes are constructed by calling

2553-415: Is not script-like since an application starts at the function named main which need not be at the top of the code. The following code starts at main , then calls printHelloWorld which prints "Hello World". In contrast, the following Python code prints "Hello World" without the main function or other syntax such as a class definition required by Java. Scripts are often created or modified by

2622-610: Is slow, inconsistent and buggy [and it has] has many corner cases and oddities. Code that works around those may need to be changed. Code that uses locals() for simple templating, or print debugging, will continue to work correctly." Some (more) standard library modules and many deprecated classes, functions and methods, will be removed in Python 3.15 or 3.16. Python 3.14 is now in alpha 2; regarding possible change to annotations: "In Python 3.14, from __future__ import annotations will continue to work as it did before, converting annotations into strings." PEP 711 proposes PyBI:

2691-586: Is sometimes used in a wider sense, to refer to dynamic high-level programming languages in general. Some are strictly interpreted languages , while others use a form of compilation. In this context, the term script refers to a small program in such a language; typically, contained in a single file, and no larger than a few thousand lines of code. The scope of scripting languages ranges from small to large, and from highly domain-specific language to general-purpose programming languages . A language may start as small and highly domain-specific and later develop into

2760-543: Is summarized in the Zen of Python (PEP 20), which includes aphorisms such as: However, Python features regularly violate these principles and have received criticism for adding unnecessary language bloat. Responses to these criticisms are that the Zen of Python is a guideline rather than a rule. The addition of some new features had been so controversial that Guido van Rossum resigned as Benevolent Dictator for Life following vitriol over

2829-460: Is that an assignment statement such as a = 1 cannot form part of the conditional expression of a conditional statement. Methods on objects are functions attached to the object's class; the syntax instance . method ( argument ) is, for normal methods and functions, syntactic sugar for Class . method ( instance , argument ) . Python methods have an explicit self parameter to access instance data , in contrast to

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2898-548: The decimal module provides decimal floating-point numbers to a pre-defined arbitrary precision and several rounding modes. The Fraction class in the fractions module provides arbitrary precision for rational numbers . Due to Python's extensive mathematics library, and the third-party library NumPy that further extends the native capabilities, it is frequently used as a scientific scripting language to aid in problems such as numerical data processing and manipulation. "Hello, World!" program : Program to calculate

2967-570: The | union type operator and the match and case keywords (for structural pattern matching statements). 3.11 expanded exception handling functionality. Python 3.12 added the new keyword type . Notable changes in 3.11 from 3.10 include increased program execution speed and improved error reporting. Python 3.11 claims to be between 10 and 60% faster than Python 3.10, and Python 3.12 adds another 5% on top of that. It also has improved error messages (again improved in 3.14), and many other changes. Python 3.13 introduces more syntax for types,

3036-566: The IBM CMS product . PROFILE EXEC is an EXEC that is automatically executed when a user logs on to tailor their environment. A simple PROFILE EXEC might look like the following: Scripting language Originally, scripting was limited to automating an operating system shell and languages were relatively simple. Today, scripting is more pervasive and some languages include modern features that allow them to be used for application development as well as scripting. A scripting language can be

3105-466: The Maya Embedded Language , or Blender which uses Python to fill this role. Some other types of applications that need faster feature addition or tweak-and-run cycles (e.g. game engines ) also use an embedded language. During the development, this allows them to prototype features faster and tweak more freely, without the need for the user to have intimate knowledge of the inner workings of

3174-487: The global interpreter lock (GIL), allowing threads to run more concurrently, that latter feature enabled with python3.13t or python3.13t.exe . Python 3.13 introduces some change in behavior, i.e. new "well-defined semantics", fixing bugs (plus many removals of deprecated classes, functions and methods, and removed some of the C ;API and outdated modules): "The [old] implementation of locals() and frame.f_locals

3243-586: The machine learning community. Python was conceived in the late 1980s by Guido van Rossum at Centrum Wiskunde & Informatica (CWI) in the Netherlands as a successor to the ABC programming language, which was inspired by SETL , capable of exception handling and interfacing with the Amoeba operating system. Its implementation began in December ;1989. Van Rossum shouldered sole responsibility for

3312-615: The 1960s to enable remote operation of the first time-sharing systems, and these used shell scripts , which controlled running computer programs within a computer program, the shell. Calvin Mooers in his TRAC language is generally credited with inventing command substitution , the ability to embed commands in scripts that, when interpreted, insert a character string into the script. Multics calls these active functions . Louis Pouzin wrote an early processor for command scripts called RUNCOM for CTSS around 1964. Stuart Madnick at MIT wrote

3381-1064: The OS version, WSH and the default script engines (VBScript and JScript) are available. Programmable calculators can be programmed in glue languages in three ways. For example, the Texas Instruments TI-92 , by factory default can be programmed with a command script language. Inclusion of the scripting and glue language Lua in the TI-NSpire series of calculators could be seen as a successor to this. The primary on-board high-level programming languages of most graphing calculators (most often Basic variants, sometimes Lisp derivatives, and more uncommonly, C derivatives) in many cases can glue together calculator functions—such as graphs, lists, matrices, etc. Third-party implementations of more comprehensive Basic version that may be closer to variants listed as glue languages in this article are available—and attempts to implement Perl, Rexx, or various operating system shells on

3450-403: The Python community is pythonic , which has a wide range of meanings related to program style. "Pythonic" code may use Python idioms well, be natural or show fluency in the language, or conform with Python's minimalist philosophy and emphasis on readability. Code that is difficult to understand or reads like a rough transcription from another programming language is called unpythonic . Python

3519-481: The TI and HP graphing calculators are also mentioned. PC-based C cross-compilers for some of the TI and HP machines used with tools that convert between C and Perl, Rexx, AWK, and shell scripts to Perl, Modern Pascal, VBScript to and from Perl make it possible to write a program in a glue language for eventual implementation (as a compiled program) on the calculator. A number of text editors support macros written either using

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3588-497: The addition of the assignment expression operator in Python 3.8. Nevertheless, rather than building all of its functionality into its core, Python was designed to be highly extensible via modules. This compact modularity has made it particularly popular as a means of adding programmable interfaces to existing applications. Van Rossum's vision of a small core language with a large standard library and easily extensible interpreter stemmed from his frustrations with ABC , which espoused

3657-475: The advent of graphical user interfaces, a specialized kind of scripting language emerged for controlling a computer. These languages interact with the same graphic windows, menus, buttons, and so on, that a human user would. They do this by simulating the actions of a user. These languages are typically used to automate user actions. Such languages are also called " macros " when control is through simulated key presses or mouse clicks, as well as tapping or pressing on

3726-429: The application or to rebuild it after each tweak (which can take a significant amount of time). The scripting languages used for this purpose range from the more common and more famous Lua and Python to lesser-known ones such as AngelScript and Squirrel . Python (computer language) Python is a high-level , general-purpose programming language . Its design philosophy emphasizes code readability with

3795-445: The automation facilities of an underlying system. Embedding of such general-purpose scripting languages instead of developing a new language for each application also had obvious benefits, relieving the application developer of the need to code a language translator from scratch and allowing the user to apply skills learned elsewhere. Some software incorporates several different scripting languages. Modern web browsers typically provide

3864-509: The behavior of system programs (in this sense, one might think of shells as being descendants of IBM's JCL, or Job Control Language , which was used for exactly this purpose). Many of these languages' interpreters double as command-line interpreters such as the Unix shell or the MS-DOS COMMAND.COM . Others, such as AppleScript offer the use of English-like commands to build scripts. With

3933-475: The class (for example, SpamClass () or EggsClass () ), and the classes are instances of the metaclass type (itself an instance of itself), allowing metaprogramming and reflection . Before version 3.0, Python had two kinds of classes (both using the same syntax): old-style and new-style ; current Python versions only support the semantics of the new style. Python supports optional type annotations . These annotations are not enforced by

4002-399: The cost of clarity. Execution speed can be improved by moving speed-critical functions to extension modules written in languages such as C, or by using a just-in-time compiler like PyPy . It is also possible to cross-compile to other languages , but it either doesn't provide the full speed-up that might be expected, since Python is a very dynamic language , or a restricted subset of Python

4071-609: The implicit self (or this ) in some other object-oriented programming languages (e.g., C++ , Java , Objective-C , Ruby ). Python also provides methods, often called dunder methods (due to their names beginning and ending with double-underscores), to allow user-defined classes to modify how they are handled by native operations including length, comparison, in arithmetic operations and type conversion. Python uses duck typing and has typed objects but untyped variable names. Type constraints are not checked at compile time ; rather, operations on an object may fail, signifying that it

4140-507: The language, but may be used by external tools such as mypy to catch errors. Mypy also supports a Python compiler called mypyc, which leverages type annotations for optimization. 1.33333 Python has the usual symbols for arithmetic operators ( + , - , * , / ), the floor division operator // and the modulo operation % (where the remainder can be negative, e.g. 4 % -3 == -2 ). It also has ** for exponentiation , e.g. 5**3 == 125 and 9**0.5 == 3.0 , and

4209-432: The large and programming in the small ". In this view, scripting is glue code , connecting software components , and a language specialized for this purpose is a glue language . Pipelines and shell scripting are archetypal examples of glue languages, and Perl was initially developed to fill this same role. Web development can be considered a use of glue languages, interfacing between a database and web server . But if

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4278-515: The operating system or application. When the GUI provides the appropriate interfaces, as in the IBM Workplace Shell , a generic scripting language, e.g. OREXX , can be used for writing GUI scripts. Application specific languages can be split in many different categories, i.e. standalone based app languages (executable) or internal application specific languages (postscript, xml, gscript as some of

4347-458: The opposite approach. Python claims to strive for a simpler, less-cluttered syntax and grammar while giving developers a choice in their coding methodology. In contrast to Perl 's " there is more than one way to do it " motto, Python embraces a "there should be one—and preferably only one—obvious way to do it." philosophy. In practice, however, Python provides many ways to achieve the same task. There are, for example, at least three ways to format

4416-491: The person executing them, but they are also often distributed, such as when large portions of games are written in a scripting language, notably the Google Chrome T-rex game. Early mainframe computers (in the 1950s) were non-interactive, instead using batch processing . IBM's Job Control Language (JCL) is the archetype of languages used to control batch processing. The first interactive shells were developed in

4485-433: The project, as the lead developer, until 12 July 2018, when he announced his "permanent vacation" from his responsibilities as Python's " benevolent dictator for life " (BDFL), a title the Python community bestowed upon him to reflect his long-term commitment as the project's chief decision-maker (he has since come out of retirement and is self-titled "BDFL-emeritus"). In January 2019, active Python core developers elected

4554-559: The standardization of the language as ECMAScript has made it popular as a general-purpose embeddable language. In particular, the Mozilla implementation SpiderMonkey is embedded in several environments such as the Yahoo! Widget Engine . Other applications embedding ECMAScript implementations include the Adobe products Adobe Flash ( ActionScript ) and Adobe Acrobat (for scripting PDF files). Tcl

4623-411: The use of significant indentation . Python is dynamically typed and garbage-collected . It supports multiple programming paradigms , including structured (particularly procedural ), object-oriented and functional programming . It is often described as a "batteries included" language due to its comprehensive standard library . Guido van Rossum began working on Python in the late 1980s as

4692-444: The widely distributed scripts, respectively implemented by Adobe, MS and Google) among others include an idiomatic scripting language tailored to the needs of the application user. Likewise, many computer game systems use a custom scripting language to express the programmed actions of non-player characters and the game environment. Languages of this sort are designed for a single application; and, while they may superficially resemble

4761-451: Was created as an extension language but has come to be used more frequently as a general-purpose language in roles similar to Python , Perl , and Ruby . On the other hand, Rexx was originally created as a job control language, but is widely used as an extension language as well as a general-purpose language. Perl is a general-purpose language, but had the Oraperl (1990) dialect, consisting of

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