code: def _fillna_prep(values, mask=None, dtype=None):
      # boilerplate for pad_1d, backfill_1d, pad_2d, backfill_2d
      if dtype is None:
          dtype = values.dtype
  
      if mask is None:
          # This needs to occur before datetime/timedeltas are cast to int64
          mask = isna(values)
  
      values = _cast_values_for_fillna(values, dtype)
  
      mask = mask.view(np.uint8)
      return values, mask
  
imports: from distutils.version import LooseVersion
  import operator
  import numpy
  from pandas._libs import algos, lib
  from pandas.compat import range, string_types
  from pandas.core.dtypes.cast import infer_dtype_from_array
  from pandas.core.dtypes.common import ensure_float64, is_datetime64_dtype, is_datetime64tz_dtype, is_float_dtype, is_integer, is_integer_dtype, is_numeric_v_string_like, is_scalar, is_timedelta64_dtype, needs_i8_conversion
  from pandas.core.dtypes.missing import isna
label_desc: Use image node_id 10 for calling a global function with example usage: _fillna_prep(values, mask, dtype) and returns: values,  mask