code: def mode_str_to_int(modestr):
      
      mode = 0
      for iteration, char in enumerate(reversed(modestr[-6:])):
          mode += int(char) << iteration * 3
      # END for each char
      return mode
docs: :param modestr: string like 755 or 644 or 100644 - only the last 6 chars will be used
      :return:
          String identifying a mode compatible to the mode methods ids of the
          stat module regarding the rwx permissions for user, group and other,
          special flags and file system flags, i.e. whether it is a symlink
          for example.