code: def unsplit(self, extra_shape, inputs, lengths):
      N = sum(lengths)
      output = np.zeros((N,) + extra_shape)
      K = len(lengths)
      assert len(inputs) == K
      current = 0
      for i in range(0, K):
          for j in range(0, lengths[i]):
              output[current] = inputs[i][j]
              current += 1
      return output
  
imports: from functools import partial
  from hypothesis import given, settings
  import numpy
  import unittest
  import hypothesis.strategies
  from caffe2.python import core, workspace
  import caffe2.python.hypothesis_test_util
  import caffe2.python.serialized_test.serialized_test_util
label_desc: Use image node_id 2 for calling the LengthsTester obj's underlying member method code with example usage: obj.unsplit(extra_shape, inputs, lengths) and returns: output