code: def chat_post_message(self, channel, text, **params):
          
          method = 'chat.postMessage'
          params.update({
              'channel': channel,
              'text': text,
          })
          return self._make_request(method, params)
docs: chat.postMessage
  
          This method posts a message to a channel.
  
          https://api.slack.com/methods/chat.postMessage