class_docstr: Unit test multi decorator Class
  TODO: Docstring
docstr: Unit test assign contributions
docstr_tok: ["Unit","test","assign","contributions"]
code: def test_assign_contributions(self):
      """
      Unit test assign contributions
      """
      backend = Mock()
      backend.assign_contributions = Mock(
          side_effect=[
              {"a": 1, "b": 2},
              {"a": 3, "b": 4},
              {"a": 5, "b": 6},
          ]
      )
      state = MultiDecorator(backend)
      output = state.assign_contributions([1, 2, 3])
      expected = {"a": [1, 3, 5], "b": [2, 4, 6]}
      self.assertDictEqual(output, expected)
  
imports: import unittest
  from unittest.mock import patch, Mock
  import numpy
  import pandas
  from shapash.explainer.multi_decorator import MultiDecorator
label_desc: Use image node_id 6 for calling the TestMultiDecorator obj's underlying member method code with example usage: obj.test_assign_contributions() without return types