code: def test_pickle(expr):
      x = eval(expr)
      f = io.BytesIO()
      pickle.dump(x, f)
      f.seek(0)
      y = pickle.load(f)
      assert y is x
  
imports: import io
  import pickle
  import pytest
  from funsor.domains import Bint, Real, Reals
label_desc: Use image node_id 2 for calling a global function with example usage: test_pickle(expr) without return types