docstr: Find the expected value for a call to ragged_segment_<aggregate>.
  
  Args:
    data: The input RaggedTensor, expressed as a nested python list.
    segment_ids: The segment ids, as a python list of ints.
    num_segments: The number of segments, as a python int.
    combiner: The Python function used to combine values.
  Returns:
    The expected value, as a nested Python list.
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code: def expected_value(self, data, segment_ids, num_segments, combiner):
      """Find the expected value for a call to ragged_segment_<aggregate>.
  
      Args:
        data: The input RaggedTensor, expressed as a nested python list.
        segment_ids: The segment ids, as a python list of ints.
        num_segments: The number of segments, as a python int.
        combiner: The Python function used to combine values.
      Returns:
        The expected value, as a nested Python list.
      """
      self.assertLen(data, len(segment_ids))
  
      # Build an empty (num_segments x ncols) "grouped" matrix
      ncols = max(len(row) for row in data)
      grouped = [
          [[] for _ in range(ncols)] for row in range(num_segments)
      ]
  
      # Append values from data[row] to grouped[segment_ids[row]]
      for row in range(len(data)):
          for col in range(len(data[row])):
              grouped[segment_ids[row]][col].append(data[row][col])
  
      # Combine the values.
      return [
          [combiner(values) for values in grouped_row if values]
          for grouped_row in grouped
      ]
  
imports: import math
  from absl.testing import parameterized
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import errors
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops.ragged import ragged_factory_ops
  from tensorflow.python.ops.ragged import ragged_math_ops
  from tensorflow.python.ops.ragged import ragged_tensor
  from tensorflow.python.platform import googletest
label_desc: Use image node_id 1 for calling the RaggedSegmentOpsTest obj's underlying member method code with example usage: obj.expected_value(data, segment_ids, num_segments, combiner) and returns: unknown