def METHOD_NAME(self):
    dict_a = {'variable_one': np.random.randn(10),
              'variable_two': np.random.randn(15)}
    dict_b = {'variable_one': np.random.randn(20),
              'variable_two': np.random.randn(20)}
    dict_c = {'variable_one': np.random.randn(10, 10),
              'variable_two': np.random.randn(15, 15)}
    dict_d = {'variable_one': np.random.randn(20, 10),
              'variable_two': np.random.randn(20, 15)}
    dict_e = {}
    dict_a_b = PhotonDataHelper.join_dictionaries(dict_a, dict_b)
    dict_c_d = PhotonDataHelper.join_dictionaries(dict_c, dict_d)
    dict_e_a = PhotonDataHelper.join_dictionaries(dict_e, dict_a)
    self.assertEqual(len(dict_a_b['variable_one']), 30)
    self.assertEqual(len(dict_a_b['variable_two']), 35)
    self.assertEqual(dict_c_d['variable_one'].shape, (30, 10))
    self.assertEqual(dict_c_d['variable_two'].shape, (35, 15))
    self.assertEqual(len(dict_e_a['variable_one']), 10)
    self.assertEqual(len(dict_e_a['variable_two']), 15)