code: def length_prepend(byte_string):
      '''
      bytes -> bytes
      '''
      length = tx.VarInt(len(byte_string))
      return length.to_bytes() + byte_strinf length_prepend(byte_string):
      '''
      bytes -> bytes
      '''
      length = tx.VarInt(len(byte_string))
      return length.to_bytes() + byte_string
docs: bytes -> bytes