code: def test_cell_px_var_expand(self):
      ip = get_ipython()
      v = self.client[-1:]
      v.activate()
      v.block = True
      ip.user_ns["x"] = "client"
      v["x"] = "engine"
      ip.user_ns["out_name"] = "theoutput"
      ip.run_cell_magic("px", "-o {out_name}", 'y=f"{x}"')
      assert v["y"] == ["engine"]
      assert "theoutput" in ip.user_ns
      assert isinstance(ip.user_ns["theoutput"], ipp.AsyncResult)
  
imports: import re
  import signal
  import sys
  import time
  import pytest
  from IPython import get_ipython
  from IPython.utils.io import capture_output
  import ipyparallel
  from ipyparallel import AsyncResult
  from .clienttest import ClusterTestCase, generate_output, raises_remote
label_desc: Use image node_id 3 for calling the TestParallelMagics obj's underlying member method code with example usage: obj.test_cell_px_var_expand() without return types