code: def collect(self):
          
          with SCCallSiteSync(self.context) as css:
              sock_info = self.ctx._jvm.PythonRDD.collectAndServe(self._jrdd.rdd())
          return list(_load_from_socket(sock_info, self._jrdd_deserializer))
docs: Return a list that contains all of the elements in this RDD.
  
          .. note:: This method should only be used if the resulting array is expected
              to be small, as all the data is loaded into the driver's memory.