code: def test_nan(self):
      # test if function ignores nan values
      x = pd.Series(
          [
              -76.0,
              41.0,
              -43.0,
              -152.0,
              -89.0,
              28.0,
              49.0,
              298.0,
              -132.0,
              146.0,
              -107.0,
              -26.0,
              26.0,
              -81.0,
              116.0,
              -217.0,
              -102.0,
              144.0,
              120.0,
              -130.0,
          ],
      )
      x = pd.concat([x, pd.Series([np.nan] * 20)])
      first_outliers = [
          -152.0,
          298.0,
          146.0,
          116.0,
          -217.0,
          144.0,
          120.0,
      ]
      primitive_instance = self.primitive(1)
      primitive_func = primitive_instance.get_function()
      assert primitive_func(x) == len(x) - len(first_outliers) - 20
  
      # test a series with all nan values
      x = pd.Series([np.nan] * 20)
  
      primitive_instance = self.primitive(1)
      primitive_func = primitive_instance.get_function()
      assert primitive_func(x) == 0
  
imports: import numpy
  import pandas
  from pytest import raises
  from featuretools.primitives import CountAboveMean, CountGreaterThan, CountInsideNthSTD, CountInsideRange, CountLessThan, CountOutsideNthSTD, CountOutsideRange
  from featuretools.tests.primitive_tests.utils import PrimitiveTestBase
label_desc: Use image node_id 3 for calling the TestCountInsideNthSTD obj's underlying member method code with example usage: obj.test_nan() without return types