code: func (b *Bot) EditCaption(originalMsg Editable, caption string) (*Message, error) {
  	messageID, chatID := originalMsg.MessageSig()
  
  	params := map[string]string{"caption": caption}
  
  	// if inline message
  	if chatID == 0 {
  		params["inline_message_id"] = messageID
  	} else {
  		params["chat_id"] = strconv.FormatInt(chatID, 10)
  		params["message_id"] = messageID
  	}
  
  	respJSON, err := b.Raw("editMessageCaption", params)
  	if err != nil {
  		return nil, err
  	}
  
  	return extractMsgResponse(respJSON)
  }
docs: // EditCaption used to edit already sent photo caption with known recepient and message id.
  //
  // On success, returns edited message object