code: def na_val(dtype):
      if dtype.storage == "pyarrow_numpy":
          return np.nan
      else:
          return pd.NA
  
imports: import operator
  import numpy
  import pytest
  from pandas.compat.pyarrow import pa_version_under12p0
  from pandas.core.dtypes.common import is_dtype_equal
  import pandas
  import pandas._testing
  from pandas.core.arrays.string_arrow import ArrowStringArray, ArrowStringArrayNumpySemantics
label_desc: Use image node_id 1 for calling a global function with example usage: na_val(dtype) and returns: np, pd