code: def list_file_extensions(path: str, reportevery: int = 1) -> List[str]:
      
      extensions = set()
      count = 0
      for root, dirs, files in os.walk(path):
          count += 1
          if count % reportevery == 0:
              log.debug("Walking directory {}: {!r}", count, root)
          for file in files:
              filename, ext = os.path.splitext(file)
              extensions.add(ext)
      return sorted(list(extensions))
docs: Returns a sorted list of every file extension found in a directory
      and its subdirectories.
  
      Args:
          path: path to scan
          reportevery: report directory progress after every *n* steps
  
      Returns:
          sorted list of every file extension found