Saves symbol to a JSON string.

        See Also
        --------
        symbol.load_json : Used to load symbol from JSON string.

def tojson(self):
        """Saves symbol to a JSON string.

        See Also
        --------
        symbol.load_json : Used to load symbol from JSON string.
        """
        json_str = ctypes.c_char_p()
        check_call(_LIB.MXSymbolSaveToJSON(self.handle, ctypes.byref(json_str)))
        return py_str(json_str.value)