code: def xstrip(filename):
    
    while xisabs(filename):
      # strip windows drive with all slashes
      if re.match(b'\\w:[\\\\/]', filename):
        filename = re.sub(b'^\\w+:[\\\\/]+', b'', filename)
      # strip all slashes
      elif re.match(b'[\\\\/]', filename):
        filename = re.sub(b'^[\\\\/]+', b'', filename)
    return filename
docs: Make relative path out of absolute by stripping
        prefixes used on Linux, OS X and Windows.
  
        This function is critical for security.