code: func (c *Context) DefaultQuery(key, defaultValue string) string {
  	if value, ok := c.GetQuery(key); ok {
  		return value
  	}
  	return defaultValue
  }
docs: // DefaultQuery returns the keyed url query value if it exists,
  // otherwise it returns the specified defaultValue string.
  // See: Query() and GetQuery() for further information.
  //     GET /?name=Manu&lastname=
  //     c.DefaultQuery("name", "unknown") == "Manu"
  //     c.DefaultQuery("id", "none") == "none"
  //     c.DefaultQuery("lastname", "none") == ""