code: func (r *EchoResponse) StandardCard(title string, content string, smallImg string, largeImg string) *EchoResponse {
  	r.Response.Card = &EchoRespPayload{
  		Type:    "Standard",
  		Title:   title,
  		Content: content,
  	}
  
  	if smallImg != "" {
  		r.Response.Card.Image.SmallImageURL = smallImg
  	}
  
  	if largeImg != "" {
  		r.Response.Card.Image.LargeImageURL = largeImg
  	}
  
  	return r
  }
docs: // StandardCard will indicate that a card should be shown in the Alexa companion app as part of the response.
  // The card shown will include the provided title and content as well as images loaded from the locations provided
  // as remote locations.