gh-127541: Update os.walk example (GH-127765)

Update os.walk example to be more modern, skip `__pycache__` dirs rather than `CVS` dirs.
(cherry picked from commit a594998)

Co-authored-by: Totosuki <[email protected]>
Co-authored-by: Bénédikt Tran <[email protected]>

Author: 2 people

Doc/library/os.rst

@@ -3547,16 +3547,16 @@ features:
 
    This example displays the number of bytes taken by non-directory files in each
    directory under the starting directory, except that it doesn't look under any
-   CVS subdirectory::
+   ``__pycache__`` subdirectory::
 
       import os
       from os.path import join, getsize
-      for root, dirs, files in os.walk('python/Lib/email'):
+      for root, dirs, files in os.walk('python/Lib/xml'):
           print(root, "consumes", end=" ")
           print(sum(getsize(join(root, name)) for name in files), end=" ")
           print("bytes in", len(files), "non-directory files")
-          if 'CVS' in dirs:
-              dirs.remove('CVS')  # don't visit CVS directories
+          if '__pycache__' in dirs:
+              dirs.remove('__pycache__')  # don't visit __pycache__ directories
 
    In the next example (simple implementation of :func:`shutil.rmtree`),
    walking the tree bottom-up is essential, :func:`rmdir` doesn't allow
@@ -3609,16 +3609,16 @@ features:
 
    This example displays the number of bytes taken by non-directory files in each
    directory under the starting directory, except that it doesn't look under any
-   CVS subdirectory::
+   ``__pycache__`` subdirectory::
 
       import os
-      for root, dirs, files, rootfd in os.fwalk('python/Lib/email'):
+      for root, dirs, files, rootfd in os.fwalk('python/Lib/xml'):
           print(root, "consumes", end="")
           print(sum([os.stat(name, dir_fd=rootfd).st_size for name in files]),
                 end="")
           print("bytes in", len(files), "non-directory files")
-          if 'CVS' in dirs:
-              dirs.remove('CVS')  # don't visit CVS directories
+          if '__pycache__' in dirs:
+              dirs.remove('__pycache__')  # don't visit __pycache__ directories
 
    In the next example, walking the tree bottom-up is essential:
    :func:`rmdir` doesn't allow deleting a directory before the directory is

Lib/os.py

@@ -335,12 +335,12 @@ def walk(top, topdown=True, onerror=None, followlinks=False):
 
     import os
     from os.path import join, getsize
-    for root, dirs, files in os.walk('python/Lib/email'):
+    for root, dirs, files in os.walk('python/Lib/xml'):
         print(root, "consumes ")
         print(sum(getsize(join(root, name)) for name in files), end=" ")
         print("bytes in", len(files), "non-directory files")
-        if 'CVS' in dirs:
-            dirs.remove('CVS')  # don't visit CVS directories
+        if '__pycache__' in dirs:
+            dirs.remove('__pycache__')  # don't visit __pycache__ directories
 
     """
     sys.audit("os.walk", top, topdown, onerror, followlinks)
@@ -466,13 +466,13 @@ def fwalk(top=".", topdown=True, onerror=None, *, follow_symlinks=False, dir_fd=
         Example:
 
         import os
-        for root, dirs, files, rootfd in os.fwalk('python/Lib/email'):
+        for root, dirs, files, rootfd in os.fwalk('python/Lib/xml'):
             print(root, "consumes", end="")
             print(sum(os.stat(name, dir_fd=rootfd).st_size for name in files),
                   end="")
             print("bytes in", len(files), "non-directory files")
-            if 'CVS' in dirs:
-                dirs.remove('CVS')  # don't visit CVS directories
+            if '__pycache__' in dirs:
+                dirs.remove('__pycache__')  # don't visit __pycache__ directories
         """
         sys.audit("os.fwalk", top, topdown, onerror, follow_symlinks, dir_fd)
         top = fspath(top)