Build an appropriate error message from a given option and
    a list of expected values.

def _error_msg_network(option, expected):
    '''
    Build an appropriate error message from a given option and
    a list of expected values.
    '''
    msg = 'Invalid network setting -- Setting: {0}, Expected: [{1}]'
    return msg.format(option, '|'.join(str(e) for e in expected))