Hacktoberfest: adding doctest to radix_sort.py file (#2779)

* adding doctest to radix_sort.py file

* fixup! Format Python code with psf/black push

* Update radix_sort.py

* Update radix_sort.py

* fixup! Format Python code with psf/black push

* Update radix_sort.py

* line

* fix tests
Co-authored-by: Ngithub-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: NJohn Law <johnlaw.po@gmail.com>

sorts/radix_sort.py

+"""
+This is a pure Python implementation of the quick sort algorithm
+For doctests run following command:
+python -m doctest -v radix_sort.py
+or
+python3 -m doctest -v radix_sort.py
+For manual testing run:
+python radix_sort.py
+"""
 from __future__ import annotations
 
+from typing import List
 
-def radix_sort(list_of_ints: list[int]) -> list[int]:
+
+def radix_sort(list_of_ints: List[int]) -> List[int]:
     """
-    radix_sort(range(15)) == sorted(range(15))
+    Examples:
+    >>> radix_sort([0, 5, 3, 2, 2])
+    [0, 2, 2, 3, 5]
+
+    >>> radix_sort(list(range(15))) == sorted(range(15))
     True
-    radix_sort(reversed(range(15))) == sorted(range(15))
+    >>> radix_sort(list(range(14,-1,-1))) == sorted(range(15))
     True
-    radix_sort([1,100,10,1000]) == sorted([1,100,10,1000])
+    >>> radix_sort([1,100,10,1000]) == sorted([1,100,10,1000])
     True
     """
     RADIX = 10
@@ -29,3 +44,9 @@ def radix_sort(list_of_ints: list[int]) -> list[int]:
         # move to next
         placement *= RADIX
     return list_of_ints
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()