Decode OP_RETURN message from vout[1]

def read_tx_opreturn(vout: dict) -> bytes:
    '''Decode OP_RETURN message from vout[1]'''

    asm = vout['scriptPubKey']['asm']
    n = asm.find('OP_RETURN')
    if n == -1:
        raise InvalidNulldataOutput({'error': 'OP_RETURN not found.'})
    else:
        # add 10 because 'OP_RETURN ' is 10 characters
        n += 10
        data = asm[n:]
        n = data.find(' ')
        # make sure that we don't include trailing opcodes
        if n == -1:
            return bytes.fromhex(data)
        else:
            return bytes.fromhex(data[:n])