# see PEP 448 for details
                self.write("**")
                self.set_precedence(_Precedence.EXPR, v)
                self.traverse(v)
            else:
                write_key_value_pair(k, v)
        with self.delimit("{", "}"):
            self.interleave(
                lambda: self.write(", "), write_item, zip(node.keys, node.values)
            )
    def visit_Tuple(self, node):
        with self.delimit_if(
            "(",
            ")",
            len(node.elts) == 0 or self.get_precedence(node) > _Precedence.TUPLE
        ):
            self.items_view(self.traverse, node.elts)
    unop = {"Invert": "~", "Not": "not", "UAdd": "+", "USub": "-"}
    unop_precedence = {
        "not": _Precedence.NOT,
        "~": _Precedence.FACTOR,
        "+": _Precedence.FACTOR,
        "-": _Precedence.FACTOR,
    }
    def visit_UnaryOp(self, node):
        operator = self.unop[node.op.__class__.__name__]
        operator_precedence = self.unop_precedence[operator]
        with self.require_parens(operator_precedence, node):
            self.write(operator)
            # factor prefixes (+, -, ~) shouldn't be separated
            # from the value they belong, (e.g: +1 instead of + 1)
            if operator_precedence is not _Precedence.FACTOR:
                self.write(" ")
            self.set_precedence(operator_precedence, node.operand)
            self.traverse(node.operand)
    binop = {