def METHOD_NAME(
    self, current_stream_state: MutableMapping[str, Any], latest_record: Mapping[str, Any]
) -> Mapping[str, Mapping[str, str]]:
    """Update existing stream state for particular funnel_id
    stream_state = {
        'funnel_id1_str' = {'date': 'datetime_string1'},
        'funnel_id2_str' = {'date': 'datetime_string2'},
         ...
        'funnel_idX_str' = {'date': 'datetime_stringX'},
    }
    NOTE: funnel_id1 type:
        - int in latest_record
        - str in current_stream_state
    """
    funnel_id: str = str(latest_record["funnel_id"])
    updated_state = latest_record[self.cursor_field]
    stream_state_value = current_stream_state.get(funnel_id, {}).get(self.cursor_field)
    if stream_state_value:
        updated_state = max(updated_state, stream_state_value)
    current_stream_state.setdefault(funnel_id, {})[self.cursor_field] = updated_state
    return current_stream_state