code: def __call__(self, a, value_df=None):
      method = getattr(self, "method", None)
      if method == "backfill":
          method = "bfill"
      elif method == "pad":
          method = "ffill"
      self._method = method
      axis = getattr(self, "axis", None) or 0
      self._axis = validate_axis(axis, a)
  
      inputs = [a]
      if value_df is not None:
          inputs.append(value_df)
      if isinstance(a, DATAFRAME_TYPE):
          return self.new_dataframe(
              inputs,
              shape=a.shape,
              dtypes=a.dtypes,
              index_value=a.index_value,
              columns_value=a.columns_value,
          )
      elif isinstance(a, SERIES_TYPE):
          return self.new_series(
              inputs,
              shape=a.shape,
              dtype=a.dtype,
              index_value=a.index_value,
              name=a.name,
          )
      else:
          return self.new_index(
              inputs,
              shape=a.shape,
              dtype=a.dtype,
              index_value=a.index_value,
              name=a.name,
              names=a.names,
          )
  
imports: import itertools
  import numpy
  import pandas
  from ...None import opcodes
  from ...config import options
  from ...core import ENTITY_TYPE, Entity, OutputType, get_output_types
  from ...core.operand import OperandStage
  from ...serialization.serializables import StringField, AnyField, BoolField, Int64Field
  from ..align import align_dataframe_dataframe, align_dataframe_series, align_series_series
  from ..core import DATAFRAME_TYPE, SERIES_TYPE
  from ..operands import DataFrameOperandMixin, DataFrameOperand
  from ..utils import validate_axis
label_desc: Use image node_id 22 for calling the FillNA obj's underlying member method code with example usage: obj.__call__(a, value_df) and returns: self, self, self