code: def get_messages(self) -> DBHandlerResponse:
      try:
          channels = self.client.conversations_list(
              types="public_channel,private_channel"
          )["channels"]
          channel_ids = {c["name"]: c["id"] for c in channels}
          response = self.client.conversations_history(
              channel=channel_ids[self.channel_name]
          )
          data_df = self._convert_json_response_to_DataFrame(response)
          return data_df
  
      except SlackApiError as e:
          assert e.response["ok"] is False
          assert e.response["error"]
          return DBHandlerResponse(data=None, error=e.response["error"])
  
file_path: evadb/evadb/third_party/databases/slack/slack_handler.py
imports: import pandas
  from slack_sdk import WebClient
  from slack_sdk.errors import SlackApiError
  from evadb.third_party.types import DBHandler, DBHandlerResponse, DBHandlerStatus
label_desc: Use image node_id 9 for calling the SlackHandler obj's underlying member method code with example usage: obj.get_messages() and returns: data_df, DBHandlerResponse