code: func (keyboard *InlineKeyboard) AddPMSwitchButton(b *Bot, text string, param string) {
  	if len(keyboard.Buttons) > 0 && len(keyboard.Buttons[0]) > 0 && keyboard.Buttons[0][0].Text == text {
  		return
  	}
  	keyboard.PrependRows(InlineButtons{InlineButton{Text: text, URL: b.PMURL(param)}})
  }
docs: // AddPMSwitchButton add the button to switch to PM as a first row in the InlineKeyboard