router.go
func (r *Router) AddHandlerBuilder(builder func(interface{}) (Handler, error)) {
	r.builders = append(r.builders, &builder)
}
func (r *Router) AddHandlerBuilder(builder func(interface{}) (Handler, error)) {
	r.builders = append(r.builders, &builder)
}
func ( r * Router ) AddHandlerBuilder ( builder func ( interface { } ) ( Handler , error ) ) { r . builders = append ( r . builders , & builder ) }
// AddHandlerBuilder adds a builder to construct handlers
AddHandlerBuilder adds a builder to construct handlers