Return an operator as a string. Currently only "=" and ":" (both synonyms)

        Arguments
        ---------
        node : parsimonious.nodes.Node.
        _ (children) : list, unused

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

        Example
        -------

        >>> BaseParser('=', default_rule='OPER').data
        '='
        >>> BaseParser(':', default_rule='OPER').data
        '='

def visit_oper(self, node, _):
        """Return an operator as a string. Currently only "=" and ":" (both synonyms)

        Arguments
        ---------
        node : parsimonious.nodes.Node.
        _ (children) : list, unused

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

        Example
        -------

        >>> BaseParser('=', default_rule='OPER').data
        '='
        >>> BaseParser(':', default_rule='OPER').data
        '='

        """

        oper = node.text
        if oper == ':':
            oper = '='
        return oper