anchor.diff:        String gistId = 'teststore';
         expect(response.status, 200);
         var data = JSON.decode(UTF8.decode(await response.body.first));
  -      expect(data['uuid'] != null, true);
  +      expect(data['uuid'], isNotNull);
         var json = {'gistId':gistId, 'internalId':data['uuid']};
         var postResponse = await _sendPostRequest(
             '_dartpadsupportservices/v1/storeGist', json);
  
positive.code:           '_dartpadsupportservices/v1/getUnusedMappingId');
        expect(response.status, 200);
        var data = JSON.decode(UTF8.decode(await response.body.first));
        expect(data['uuid'] != null, true);
        var responseTwo = await _sendGetRequest(
            '_dartpadsupportservices/v1/getUnusedMappingId');
        expect(responseTwo.status, 200);
  
negative.code:       String gistId = 'testfail';
        expect(response.status, 200);
        var data = JSON.decode(UTF8.decode(await response.body.first));
        expect(data['uuid'], isNotNull);
        var json = {'gistId':gistId, 'internalId':data['uuid']};
        var postResponse = await _sendPostRequest(
            '_dartpadsupportservices/v1/storeGist', json);
  