Remove Python 2 references from the track (#3437)

* Remove Python 2 references from the track

* Revert unintentional whitespace changes to test files

[no important files changed]

Author: IsaacG

concepts/comparisons/about.md

@@ -82,7 +82,7 @@ False
 Strings (`str`) are compared [_lexicographically_][lexographic order], using their individual Unicode code points (_the result of passing each code point in the `str` to the built-in function [`ord()`][ord], which returns an `int`_).
 If all code points in both strings match and are _**in the same order**_, the two strings are considered equal.
 This comparison is done in a 'pair-wise' fashion - first-to-first, second-to-second, etc.
-Unlike in Python 2.x, in Python 3.x, `str` and `bytes` cannot be directly coerced/compared.
+In Python 3.x, `str` and `bytes` cannot be directly coerced/compared.
 
 ```python
 >>> 'Python' > 'Rust'

concepts/string-formatting/about.md

@@ -149,7 +149,7 @@ Use of the `%` operator for formatting is the oldest method of string formatting
 It comes from the C language and allows the use of positional arguments to build a `str`.
 
 This method has been superseded by both `f-strings` and `str.format()`, which is why the nickname for `%` formatting is _'Old Style'_.
-It can be still found in python 2 and/or legacy code.
+It can be still found in Python 2 and/or legacy code.
 While using this method will work in Python 3.x, `%` formatting is usually avoided because it can be error-prone, is less efficient, has fewer options available, and any placeholder-argument mismatch can raise an exception.
 Using the `%` operator is similar to [`printf()`][printf-style-docs], so it is also sometimes called _printf formatting_.
 

docs/ABOUT.md

@@ -22,7 +22,7 @@ The [zen of Python (PEP 20)][the zen of python] and [What is Pythonic?][what is
 
 Tests and tooling for this track currently support `3.7` - `3.10.6` (_tests_) and [`Python 3.11`][311-new-features] (_tooling_).
 It is highly recommended that students upgrade to at least `Python 3.8`, as some features used by this track may not be supported in earlier versions.
-That being said, most of the exercises will work with `Python 3.6+`, and many are compatible with `Python 2.7+`.
+That being said, most of the exercises will work with `Python 3.6+`.
 But we don't guarantee support for versions not listed under [Active Python Releases][active-python-releases].
 We will try to note when a feature is only available in a certain version.
 

docs/INSTALLATION.md

@@ -6,7 +6,7 @@ Real Python also offers a [nice guide][helpful guide] to installation on various
 Finally, these posts by Brett Cannon [A quick-and-dirty guide][quick-and-dirty] and [Why you should use `python -m pip`][python-m-pip], give very helpful advice on how to manage Python installations and packages.
 
 **Note for MacOS users:**  prior to MacOS Monterey (12.3), `Python 2.7` came pre-installed with the operating system.
-Using `Python 2.7` with Exercism or most other programs is not recommended.
+Using `Python 2.7` with Exercism or most other programs is not supported.
 You should instead install [Python 3][Python-three downloads] via one of the methods detailed below.
 As of MacOS Monterey (12.3), no version of Python will be pre-installed via MacOS.
 
@@ -20,7 +20,7 @@ Some quick links into the documentation by operating system:
 
 Exercism tests and tooling currently support `3.7` - `3.10.6` (_tests_) and [`Python 3.11`][311-new-features] (_tooling_).
 Exceptions to this support are noted where they occur.
-Most of the exercises will work with `Python 3.6+`, and many are compatible with `Python 2.7+`.
+Most of the exercises will work with `Python 3.6+`.
 But we don't guarantee support for versions not listed under [Active Python Releases][active-python-releases].
 
 

exercises/concept/black-jack/.docs/introduction.md

@@ -80,7 +80,7 @@ False
 Unlike numbers, strings (`str`) are compared [_lexicographically_][lexographic order], using their individual Unicode code points (_the result of passing each code point in the `str` to the built-in function [`ord()`][ord], which returns an `int`_).
 If all code points in both strings match and are _**in the same order**_, the two strings are considered equal.
 This comparison is done in a 'pair-wise' fashion - first-to-first, second-to-second, etc.
-Unlike in Python 2.x, in Python 3.x, `str` and `bytes` cannot be directly coerced/compared.
+In Python 3.x, `str` and `bytes` cannot be directly coerced/compared.
 
 ```python
 >>> 'Python' > 'Rust'

exercises/practice/circular-buffer/.meta/example.py

@@ -25,7 +25,7 @@ def __init__(self, capacity):
         self.read_point = 0
         self.write_point = 0
 
-    # (protected) helper method to support python 2/3
+    # (protected) helper method
     def _update_buffer(self, data):
         try:
             self.buffer[self.write_point] = data

exercises/practice/pythagorean-triplet/.meta/template.j2

@@ -2,9 +2,6 @@
 
 {{ macros.header() }}
 
-# Python 2/3 compatibility
-if not hasattr(unittest.TestCase, 'assertCountEqual'):
-    unittest.TestCase.assertCountEqual = unittest.TestCase.assertItemsEqual
 
 class {{ exercise | camel_case }}Test(unittest.TestCase):
     {% for case in cases -%}

exercises/practice/pythagorean-triplet/pythagorean_triplet_test.py

@@ -6,10 +6,6 @@
 
 # Tests adapted from `problem-specifications//canonical-data.json`
 
-# Python 2/3 compatibility
-if not hasattr(unittest.TestCase, "assertCountEqual"):
-    unittest.TestCase.assertCountEqual = unittest.TestCase.assertItemsEqual
-
 
 class PythagoreanTripletTest(unittest.TestCase):
     def test_triplets_whose_sum_is_12(self):

exercises/practice/sublist/sublist.py

@@ -1,8 +1,7 @@
 """
 This exercise stub and the test suite contain several enumerated constants.
 
-Since Python 2 does not have the enum module, the idiomatic way to write
-enumerated constants has traditionally been a NAME assigned to an arbitrary,
+Enumerated constants can be done with a NAME assigned to an arbitrary,
 but unique value. An integer is traditionally used because it’s memory
 efficient.
 It is a common practice to export both constants and functions that work with

pylintrc

@@ -341,11 +341,6 @@ known-standard-library=
 # Force import order to recognize a module as part of a third party library.
 known-third-party=enchant, absl
 
-# Analyse import fallback blocks. This can be used to support both Python 2 and
-# 3 compatible code, which means that the block might have code that exists
-# only in one or another interpreter, leading to false positives when analysed.
-analyse-fallback-blocks=no
-
 
 [CLASSES]
 

reference/exercise-concepts/rna-transcription.md

@@ -2,7 +2,7 @@
 
 ## Example implementation
 
-Modified from the existing [example.py](https://github.com/exercism/python/blob/master/exercises/rna-transcription/example.py) to remove Python 2 compatiblity noise:
+Taken from the existing [example.py](https://github.com/exercism/python/blob/main/exercises/practice/rna-transcription/.meta/example.py):
 
 ```python
 DNA_TO_RNA = str.maketrans("AGCT", "UCGA")