code: func (c Client) CreateButton(params *Button) (*Button, error) {
  	finalParams := &struct {
  		Button *Button `json:"button"`
  	}{
  		Button: params,
  	}
  	holder := buttonHolder{}
  	if err := c.Post("buttons", finalParams, &holder); err != nil {
  		return nil, err
  	}
  	if err := checkApiErrors(holder.response, "CreateButton"); err != nil {
  		return nil, err
  	}
  	button := holder.Button
  	button.EmbedHtml = "<div class=\"coinbase-button\" data-code=\"" + button.Code + "\"></div><script src=\"https://coinbase.com/assets/button.js\" type=\"text/javascript\"></script>"
  	return &button, nil
  }
docs: // CreateButton gets a new payment button including EmbedHtml as a field on button struct