code: def test_async_call_loop_error_if_no_loop(self):
      tbl = Table({"a": int, "b": float, "c": str})
      manager = PerspectiveManager()
  
      with raises(PerspectiveError):
          # loop not set - errors
          manager.call_loop(tbl.update, data)
  
      manager.set_loop_callback(TestAsync.loop.add_callback)
      manager.call_loop(tbl.update, data)
      manager.host(tbl)
  
      @syncify
      def _task():
          return tbl.size()
  
      # subsequent calls to call_loop will work if loop_callback is set.
      assert _task() == 10
  
      tbl.delete()
  
imports: import queue
  import random
  import threading
  from functools import partial
  import tornado.ioloop
  from perspective import PerspectiveError, PerspectiveManager, Table
  from pytest import raises
label_desc: Use image node_id 7 for calling the TestAsync obj's underlying member method code with example usage: obj.test_async_call_loop_error_if_no_loop() and returns: tbl