code: def channel_name_to_id(self, channel_name, force_lookup=False):
          
          if force_lookup or not self.channel_name_id_map:
              channels = self.channels_list()['channels']
              self.channel_name_id_map = {channel['name']: channel['id'] for channel in channels}
          channel = channel_name.startswith('#') and channel_name[1:] or channel_name
          return self.channel_name_id_map.get(channel)
docs: Helper name for getting a channel's id from its name