code: def fetch_mmtf(self, pdb_code: str):
      self.code = pdb_code
      self.mmtf = fetch(pdb_code)
      df = self._mmtf_to_df(self.mmtf)
      self._df["ATOM"] = df.loc[df.record_name == "ATOM"]
      self._df["HETATM"] = df.loc[df.record_name == "HETATM"]
      return self
  
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 5 for calling the PandasMmtf obj's underlying member method code with example usage: obj.fetch_mmtf(pdb_code) and returns: self