code: func checkCache(method string, url string, bctx BuiltinContext) ast.Value {
  	key := getCtxKey(method, url)
  
  	val, ok := bctx.Cache.Get(key)
  	if ok {
  		return val.(ast.Value)
  	}
  	return nil
  }
docs: // checkCache checks for the given key's value in the cache