docstr: Assign a new value to the pandas DataFrame
code: def df(self, value: Any):
      """Assign a new value to the pandas DataFrame"""
      raise AttributeError(
          "Please use `PandasMmtf._df = ... ` instead\n"
          "of `PandasMmtf.df = ... ` if you are sure that\n"
          "you want to overwrite the `df` attribute."
      )
  
imports: from __future__ import annotations
  import os
  import copy
  import gzip
  import warnings
  from string import ascii_uppercase
  from typing import Any, Dict, List, Union
  from warnings import warn
  import numpy
  import pandas
  from looseversion import LooseVersion
  from mmtf import MMTFDecoder, MMTFEncoder, fetch, parse, parse_gzip
  from biopandas.constants import protein_letters_3to1_extended
  from ..pdb.engines import amino3to1dict, pdb_df_columns, pdb_records
label_desc: Use image node_id 3 for calling the PandasMmtf obj's underlying member method code with example usage: obj.df(value) without return types