code: def test_isna():
      assert pd.isna(NA) is True
      assert pd.notna(NA) is False
  
imports: from datetime import date, time, timedelta
  import pickle
  import numpy
  import pytest
  from pandas._libs.missing import NA
  from pandas.core.dtypes.common import is_scalar
  import pandas
  import pandas._testing
label_desc: Use image node_id 18 for calling a global function with example usage: test_isna() without return types