extend raw_validators with override_validators.
        override_validators will merge and override raw_validators.

    Args:
        raw_validators (dict):
        override_validators (dict):

    Returns:
        list: extended validators

    Examples:
        >>> raw_validators = [{'eq': ['v1', 200]}, {"check": "s2", "expect": 16, "comparator": "len_eq"}]
        >>> override_validators = [{"check": "v1", "expect": 201}, {'len_eq': ['s3', 12]}]
        >>> extend_validators(raw_validators, override_validators)
            [
                {"check": "v1", "expect": 201, "comparator": "eq"},
                {"check": "s2", "expect": 16, "comparator": "len_eq"},
                {"check": "s3", "expect": 12, "comparator": "len_eq"}
            ]

def extend_validators(raw_validators, override_validators):
    """ extend raw_validators with override_validators.
        override_validators will merge and override raw_validators.

    Args:
        raw_validators (dict):
        override_validators (dict):

    Returns:
        list: extended validators

    Examples:
        >>> raw_validators = [{'eq': ['v1', 200]}, {"check": "s2", "expect": 16, "comparator": "len_eq"}]
        >>> override_validators = [{"check": "v1", "expect": 201}, {'len_eq': ['s3', 12]}]
        >>> extend_validators(raw_validators, override_validators)
            [
                {"check": "v1", "expect": 201, "comparator": "eq"},
                {"check": "s2", "expect": 16, "comparator": "len_eq"},
                {"check": "s3", "expect": 12, "comparator": "len_eq"}
            ]

    """

    if not raw_validators:
        return override_validators

    elif not override_validators:
        return raw_validators

    else:
        def_validators_mapping = _convert_validators_to_mapping(raw_validators)
        ref_validators_mapping = _convert_validators_to_mapping(override_validators)

        def_validators_mapping.update(ref_validators_mapping)
        return list(def_validators_mapping.values())