def operator(self, node, children):
        'operator = "+" / "-" / "*" / "/"'
        operators = {'+': op.add, '-': op.sub, '*': op.mul, '/': op.div}
        return operators[node.text]
def operator ( self , node , children ) : operators = { '+' : op . add , '-' : op . sub , '*' : op . mul , '/' : op . div } return operators [ node . text ]
operator = "+" / "-" / "*" / "/"