code: def test_segment_id_and_input_empty(self):
      inputs = np.array([], dtype=np.string_)
      segment_ids = np.array([], dtype=np.int32)
      num_segments = 3
      separator = ":"
      output_array = ["", "", ""]
      res = self.evaluate(
          string_ops.unsorted_segment_join(
              inputs=inputs,
              segment_ids=segment_ids,
              num_segments=num_segments,
              separator=separator,
          )
      )
      self.assertAllEqual(res.shape, np.array(output_array).shape)
      self.assertAllEqualUnicode(res, output_array)
  
imports: from absl.testing import parameterized
  import numpy
  from tensorflow.python.eager import context
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import errors_impl
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import string_ops
  from tensorflow.python.platform import test
label_desc: Use image node_id 2 for calling the UnsortedSegmentJoinOpTest obj's underlying member method code with example usage: obj.test_segment_id_and_input_empty() without return types