extend raw_variables with override_variables.
        override_variables will merge and override raw_variables.

    Args:
        raw_variables (list):
        override_variables (list):

    Returns:
        dict: extended variables mapping

    Examples:
        >>> raw_variables = [{"var1": "val1"}, {"var2": "val2"}]
        >>> override_variables = [{"var1": "val111"}, {"var3": "val3"}]
        >>> extend_variables(raw_variables, override_variables)
            {
                'var1', 'val111',
                'var2', 'val2',
                'var3', 'val3'
            }

def extend_variables(raw_variables, override_variables):
    """ extend raw_variables with override_variables.
        override_variables will merge and override raw_variables.

    Args:
        raw_variables (list):
        override_variables (list):

    Returns:
        dict: extended variables mapping

    Examples:
        >>> raw_variables = [{"var1": "val1"}, {"var2": "val2"}]
        >>> override_variables = [{"var1": "val111"}, {"var3": "val3"}]
        >>> extend_variables(raw_variables, override_variables)
            {
                'var1', 'val111',
                'var2', 'val2',
                'var3', 'val3'
            }

    """
    if not raw_variables:
        override_variables_mapping = ensure_mapping_format(override_variables)
        return override_variables_mapping

    elif not override_variables:
        raw_variables_mapping = ensure_mapping_format(raw_variables)
        return raw_variables_mapping

    else:
        raw_variables_mapping = ensure_mapping_format(raw_variables)
        override_variables_mapping = ensure_mapping_format(override_variables)
        raw_variables_mapping.update(override_variables_mapping)
        return raw_variables_mapping