code: func (c *Context) JSONP(code int, obj interface{}) {
  	callback := c.DefaultQuery("callback", "")
  	if callback == "" {
  		c.Render(code, render.JSON{Data: obj})
  		return
  	}
  	c.Render(code, render.JsonpJSON{Callback: callback, Data: obj})
  }
docs: // JSONP serializes the given struct as JSON into the response body.
  // It add padding to response body to request data from a server residing in a different domain than the client.
  // It also sets the Content-Type as "application/javascript".