code: def testIsLoopEnter(self):
      enter = gen_control_flow_ops.enter(1, frame_name="name").op
      self.assertTrue(control_flow_util.IsLoopEnter(enter))
      self.assertFalse(control_flow_util.IsLoopConstantEnter(enter))
  
      ref_enter = gen_control_flow_ops.ref_enter(
          test_ops.ref_output(), frame_name="name"
      ).op
      self.assertTrue(control_flow_util.IsLoopEnter(ref_enter))
      self.assertFalse(control_flow_util.IsLoopConstantEnter(ref_enter))
  
      const_enter = gen_control_flow_ops.enter(
          1, frame_name="name", is_constant=True
      ).op
      self.assertTrue(control_flow_util.IsLoopEnter(const_enter))
      self.assertTrue(
          control_flow_util.IsLoopConstantEnter(const_enter)
      )
  
      self.assertFalse(
          control_flow_util.IsLoopEnter(test_ops.int_output().op)
      )
  
imports: from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import test_ops
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import cond
  from tensorflow.python.ops import control_flow_ops
  from tensorflow.python.ops import control_flow_util
  from tensorflow.python.ops import gen_control_flow_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops import while_loop
  from tensorflow.python.platform import test
label_desc: Use image node_id 2 for calling the ControlFlowUtilTest obj's underlying member method code with example usage: obj.testIsLoopEnter() without return types