code: def test_regular_halflife_avg():
      primitive_instance = ExponentialWeightedAverage(halflife=2.7)
      primitive_func = primitive_instance.get_function()
      array = pd.Series([1, 2, 7, 5])
      answer = pd.Series(primitive_func(array))
      correct_answer = pd.Series(
          [
              1.0,
              1.563830114594977,
              3.8556233149044865,
              4.2592901785684205,
          ],
      )
      pd.testing.assert_series_equal(answer, correct_answer)
  
imports: import numpy
  import pandas
  from featuretools.primitives import ExponentialWeightedAverage, ExponentialWeightedSTD, ExponentialWeightedVariance
label_desc: Use image node_id 3 for calling a global function with example usage: test_regular_halflife_avg() without return types