code: def dropna(self):
      return self._dropna
  
imports: from typing import Union, List
  import numpy
  import pandas
  from ...None import opcodes
  from ...core import recursive_tile
  from ...serialization.serializables import KeyField, AnyField, BoolField
  from ...utils import has_unknown_shape
  from ..operands import DataFrameOperand, DataFrameOperandMixin
  from ..utils import build_df, parse_index
label_desc: Use image node_id 4 for calling the DataFrameStack obj's underlying member method code with example usage: obj.dropna() and returns: self