code: def test_hyperparams_to_flat():
      dict_values = {"hp": 1, "stepa": {"hp": 2, "stepb": {"hp": 3}}}
      r = HyperparameterSamples(**dict_values)
  
      r = r.to_flat_dict()
  
      expected_dict_values = {
          "hp": 1,
          "stepa__hp": 2,
          "stepa__stepb__hp": 3,
      }
      assert r == expected_dict_values
  
file_path: Neuraxle/testing_neuraxle/test_recursive_dict.py
imports: import pytest
  from neuraxle.hyperparams.space import RecursiveDict, HyperparameterSamples
label_desc: Use image node_id 10 for calling a global function with example usage: test_hyperparams_to_flat() without return types