def has_error(json): """ Returns True if the response to a currency query encountered an error.

Given a JSON string provided by the web service, this function returns True if the query failed and there is an error message. For example, if the json is

'{"success":false,"src":"","dst":"","error":"Source currency code is invalid."}'

then this function returns True (It does NOT return the error message 'Source currency code is invalid'). On the other hand if the json is

'{"success": true, "src": "2 United States Dollars", "dst": "1.772814 Euros", "error": ""}'

then this function returns False.

The web server does NOT specify the number of spaces after the colons. The JSON

'{"success":true, "src":"2 United States Dollars", "dst":"1.772814 Euros", "error":""}'

is also valid (in addition to the examples above).

Parameter json: a json string to parse Precondition: json a string provided by the web service (ONLY enforce the type) """

Can tou help me to implement function with this spec?