code: def test_na_avg():
      primitive_instance = ExponentialWeightedAverage(com=0.5)
      primitive_func = primitive_instance.get_function()
      array = pd.Series([1, 2, 7, np.nan, 5])
      answer = pd.Series(primitive_func(array))
      correct_answer = pd.Series(
          [
              1.0,
              1.75,
              5.384615384615384,
              5.384615384615384,
              5.053191489361702,
          ],
      )
      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 5 for calling a global function with example usage: test_na_avg() without return types