code: def get_descriptor_for_layer(self, layer):
          
          if not layer in self._layer_descriptor_cache:
              params = {'f': 'pjson'}
              if self.token:
                  params['token'] = self.token
              response = requests.get(self._build_request(layer), params=params)
              self._layer_descriptor_cache[layer] = response.json()
          return self._layer_descriptor_cache[layer]
docs: Returns the standard JSON descriptor for the layer. There is a lot of
          usefule information in there.