def command_result_processor_parameter_unexpected(parameter_value):
    """
    Command result message processor if a received parameter is unexpected.
    
    Parameters
    ----------
    parameter_value : `str`
        Received parameter.
    
    Returns
    -------
    message : `str`
    """
    message_parts = []
    
    message_parts.append('Unexpected parameter: ')
    message_parts.append(repr(parameter_value))
    message_parts.append('.\n')
    
    return ''.join(message_parts)