@rule('<STR_LIT>')<EOL><INDENT>def visit_args_oper(self, _, children):<DEDENT>
return children[<NUM_LIT:0>]<EOL>
Operator to separate argument name and value.

        Arguments
        ---------
        _ (node) : parsimonious.nodes.Node.
        children : str
            - 0: The operator as a string.

        -------
        str
            The operator as a string.

        Example
        -------

        >>> NamedArgsParserMixin('=', default_rule='ARGS_OPER').data
        '='
        >>> NamedArgsParserMixin(':', default_rule='ARGS_OPER').data
        '='