code: def testRankTwo(self):
      input_array = [
          ["this", "is", "a", "test"],
          ["please", "do", "not", "panic"],
      ]
      truth_dim_zero = ["thisplease", "isdo", "anot", "testpanic"]
      truth_shape_dim_zero = [4]
      truth_dim_one = ["thisisatest", "pleasedonotpanic"]
      truth_shape_dim_one = [2]
      self._testReduceJoin(
          input_array, truth_dim_zero, truth_shape_dim_zero, axis=0
      )
      self._testReduceJoin(
          input_array, truth_dim_one, truth_shape_dim_one, axis=1
      )
  
      expected_val = "thisisatestpleasedonotpanic"
      expected_shape = []
      self._testReduceJoin(
          input_array, expected_val, expected_shape, axis=None
      )
  
      # Using axis=[] is a no-op.
      expected_val = input_array
      expected_shape = [2, 4]
      self._testReduceJoin(
          input_array, expected_val, expected_shape, axis=[]
      )
  
imports: import itertools
  import numpy
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import string_ops
  from tensorflow.python.platform import test
label_desc: Use image node_id 4 for calling the ReduceJoinTest obj's underlying member method code with example usage: obj.testRankTwo() without return types