function byId byId<T extends { id: number; }>(items: readonly T[]): Map<number, T> Key items by their own id, so a caller can look one up. Hand-rolled because @std/collections.associateBy keys by a string and gives back an object, while every caller here has number ids and wants a Map. Type Parameters T extends { id: number; } Parameters items: readonly T[] Return Type Map<number, T>