class_docstr: base class to work with chatbot memory
class_docstr_tok: ["base","class","to","work","with","chatbot","memory"]
docstr: set date to start hiding messages
docstr_tok: ["set","date","to","start","hiding","messages"]
code: def hide_history(self, chat_id, left_count):
      """
      set date to start hiding messages
      """
      history = self.get_chat_history(chat_id)
      if left_count < len(history) - 1:
          left_count = len(history) - 1
      sent_at = history[-left_count].sent_at
  
      self._hide_history_before[chat_id] = sent_at
  
imports: from mindsdb_sql.parser.ast import Identifier, Select, BinaryOperation, Constant, OrderBy
  from mindsdb.interfaces.storage import db
  from .types import ChatBotMessage
label_desc: Use image node_id 3 for calling the BaseMemory obj's underlying member method code with example usage: obj.hide_history(chat_id, left_count) without return types