code: def __delitem__(self, k: InstKT) -> None:
      self.check()
      inst = self._read_instrument()
      del inst[k]
      self._write_instrument(inst)
  
imports: import struct
  from pathlib import Path
  from typing import Iterable, Union, Dict, Mapping, Tuple, List
  import numpy
  import pandas
  from qlib.utils.time import Freq
  from qlib.utils.resam import resam_calendar
  from qlib.config import C
  from qlib.data.cache import H
  from qlib.log import get_module_logger
  from qlib.data.storage import CalendarStorage, InstrumentStorage, FeatureStorage, CalVT, InstKT, InstVT
label_desc: Use image node_id 7 for calling the FileInstrumentStorage obj's underlying member method code with example usage: obj.__delitem__(k) without return types