class_docstr: A lightweight wrapper of a dict that sends forwardMsgs when state changes.
  It stores str keys with str and List[str] values.
class_docstr_tok: ["A","lightweight","wrapper","of","a","dict","that","sends","forwardMsgs","when","state","changes",".","It","stores","str","keys","with","str","and","List","[","str","]","values","."]
code: def __delitem__(self, key: str) -> None:
      try:
          if key in EMBED_QUERY_PARAMS_KEYS:
              raise KeyError(missing_key_error_message(key))
          del self._query_params[key]
          self._send_query_param_msg()
      except KeyError:
          raise KeyError(missing_key_error_message(key))
  
imports: from dataclasses import dataclass, field
  from typing import Dict, Iterable, Iterator, List, MutableMapping, Union
  from urllib import parse
  from streamlit.constants import EMBED_QUERY_PARAMS_KEYS
  from streamlit.errors import StreamlitAPIException
  from streamlit.proto.ForwardMsg_pb2 import ForwardMsg
label_desc: Use image node_id 4 for calling the QueryParams obj's underlying member method code with example usage: obj.__delitem__(key) without return types