code: def test_exprstat(self):
      F = self.fragment("PASS")
      pass_stat = PassStatNode(pos=None)
      T = F.substitute({"PASS": pass_stat})
      self.assertTrue(isinstance(T.stats[0], PassStatNode), T)
  
file_path: catboost/contrib/tools/cython/Cython/Compiler/Tests/TestTreeFragment.py
imports: from Cython.TestUtils import CythonTest
  from Cython.Compiler.TreeFragment import *
  from Cython.Compiler.Nodes import *
  from Cython.Compiler.UtilNodes import *
  import Cython.Compiler.Naming
label_desc: Use image node_id 5 for calling the TestTreeFragments obj's underlying member method code with example usage: obj.test_exprstat() without return types