code: def test_has_frequency():
      param = HasFrequency()
      assert param.get_frequency() == "epoch"
      freq = "foobar"
      param.set_frequency(freq)
      assert param.get_frequency() == freq
  
file_path: elephas/tests/ml/test_params.py
imports: from elephas.ml.params import *
label_desc: Use image node_id 4 for calling a global function with example usage: test_has_frequency() without return types