def add_trigger_models(trigger_types):
    """
    Register trigger types.

    :param trigger_types: A list of triggers to register.
    :type trigger_types: ``list`` of ``dict``

    :rtype: ``list`` of ``tuple`` (trigger_type, trigger)
    """
    [
        r
        for r in (
            _validate_trigger_type(trigger_type) for trigger_type in trigger_types
        )
        if r is not None
    ]

    result = []
    for trigger_type in trigger_types:
        item = _add_trigger_models(trigger_type=trigger_type)

        if item:
            result.append(item)

    return result

    Register trigger types.

    :param trigger_types: A list of triggers to register.
    :type trigger_types: ``list`` of ``dict``

    :rtype: ``list`` of ``tuple`` (trigger_type, trigger)
    
st2common/st2common/services/triggers.py