new_contents: #!/usr/bin/env python
  # rename *.h to *.cpp
  
  import os
  
  for dirpath, dirnames, filenames in os.walk('.'):
      for filename in filenames:
          parts = filename.split('.')
          basename = parts[0]
          ext = '.cpp'
          os.rename(filename, basename + ext)
          print(filename)
  
subject: Add rename.py