k, v = item
            if k is None:
                # for dictionary unpacking operator in dicts {**{'y': 2}}
                # see PEP 448 for details
                self.write("**")
                self.dispatch(v)
            else:
                write_key_value_pair(k, v)
        interleave(lambda: self.write(", "), write_item, zip(t.keys, t.values))
        self.write("}")
    def _Tuple(self, t):
        self.write("(")
        if len(t.elts) == 1:
            elt = t.elts[0]
            self.dispatch(elt)
            self.write(",")
        else:
            interleave(lambda: self.write(", "), self.dispatch, t.elts)
        self.write(")")
    unop = {"Invert": "~", "Not": "not", "UAdd": "+", "USub": "-"}
    def _UnaryOp(self, t):
        self.write("(")
        self.write(self.unop[t.op.__class__.__name__])
        self.write(" ")
        self.dispatch(t.operand)
        self.write(")")
    binop = {
        "Add": "+",
        "Sub": "-",
        "Mult": "*",
        "MatMult": "@",
        "Div": "/",
        "Mod": "%",
        "LShift": "<<",
        "RShift": ">>",
        "BitOr": "|",
        "BitXor": "^",
        "BitAnd": "&",
        "FloorDiv": "//",
        "Pow": "**",
    }
    def _BinOp(self, t):
        self.write("(")
        self.dispatch(t.left)