code: def isna(obj: NDFrameT) -> NDFrameT:
      ...
  
imports: from __future__ import annotations
  from decimal import Decimal
  from functools import partial
  from typing import TYPE_CHECKING, overload
  import numpy
  from pandas._config import get_option
  from pandas._libs import lib
  import pandas._libs.missing
  from pandas._libs.tslibs import NaT, iNaT
  from pandas.core.dtypes.common import DT64NS_DTYPE, TD64NS_DTYPE, ensure_object, is_bool_dtype, is_categorical_dtype, is_complex_dtype, is_dtype_equal, is_extension_array_dtype, is_float_dtype, is_integer_dtype, is_object_dtype, is_scalar, is_string_or_object_np_dtype, needs_i8_conversion
  from pandas.core.dtypes.dtypes import CategoricalDtype, DatetimeTZDtype, ExtensionDtype, IntervalDtype, PeriodDtype
  from pandas.core.dtypes.generic import ABCDataFrame, ABCExtensionArray, ABCIndex, ABCMultiIndex, ABCSeries
  from pandas.core.dtypes.inference import is_list_like
label_desc: Use image node_id 3 for calling a global function with example usage: isna(obj) without return types