code: def get(self, resource_id=None):
          
          if request.path.endswith('meta'):
              return self._meta()
  
          if resource_id is None:
              error_message = is_valid_method(self.__model__)
              if error_message:
                  raise BadRequestException(error_message)
  
              if 'export' in request.args: 
                  return self._export(self._all_resources())
  
              return flask.jsonify({
                  self.__json_collection_name__: self._all_resources()
                  })
          else:
              resource = self._resource(resource_id)
              error_message = is_valid_method(self.__model__, resource)
              if error_message:
                  raise BadRequestException(error_message)
              return jsonify(resource)
docs: Return an HTTP response object resulting from an HTTP GET call.
  
          If *resource_id* is provided, return just the single resource.
          Otherwise, return the full collection.
  
          :param resource_id: The value of the resource's primary key