code: def _convert_na_value(ser, expected):
      if ser.dtype != object:
          if ser.dtype.storage == "pyarrow_numpy":
              expected = expected.fillna(np.nan)
          else:
              # GH#18463
              expected = expected.fillna(pd.NA)
      return expected
  
label_desc: Use image node_id 1 for calling a global function with example usage: _convert_na_value(ser, expected) and returns: expected