code: def test_contains(self):
      var1 = MyVariable("var1")
      var2 = MyVariable("var2")
      var3 = op1(var2, var1)
      var4 = op2(var3, var2)
      var5 = op3(var4, var2, var2)
      fg = FunctionGraph([var1, var2], [var3, var5], clone=False)
  
      assert var1 in fg
      assert var3 in fg
      assert var3.owner in fg
      assert var5 in fg
      assert var5.owner in fg
  
imports: import pickle
  import numpy
  import pytest
  from pytensor.configdefaults import config
  from pytensor.graph.basic import NominalVariable
  from pytensor.graph.fg import FunctionGraph
  from pytensor.graph.utils import MissingInputError
  from tests.graph.utils import MyConstant, MyOp, MyType, MyVariable, MyVariable2, op1, op2, op3
label_desc: Use image node_id 14 for calling the TestFunctionGraph obj's underlying member method code with example usage: obj.test_contains() without return types