code: def _ostaunicode_zero_pad(src, fulllen):
      # type: (str, int) -> bytes
      '''
      Internal function to create a zero-padded Identifier byte string from a
      source string.
  
      Parameters:
       src - The src string to start from.
       fulllen - The padded out length of the result.
      Returns:
       A full identifier byte string containing the source string.
      '''
      byte_src = _ostaunicode(src)
      return byte_src + b'\x00' * (fulllen - 1 - len(byte_src)) + (struct.pack('=B', len(byte_src))f _ostaunicode_zero_pad(src, fulllen):
      # type: (str, int) -> bytes
      '''
      Internal function to create a zero-padded Identifier byte string from a
      source string.
  
      Parameters:
       src - The src string to start from.
       fulllen - The padded out length of the result.
      Returns:
       A full identifier byte string containing the source string.
      '''
      byte_src = _ostaunicode(src)
      return byte_src + b'\x00' * (fulllen - 1 - len(byte_src)) + (struct.pack('=B', len(byte_src)))
docs: Internal function to create a zero-padded Identifier byte string from a
      source string.
  
      Parameters:
       src - The src string to start from.
       fulllen - The padded out length of the result.
      Returns:
       A full identifier byte string containing the source string.