Challenge 2: Write a deletePost Mutation — Possible Solution
====================================================================

// Schema

type Mutation {
  createPost(input: CreatePostInput!): Post!
  updatePost(input: UpdatePostInput!): Post!
  deletePost(id: ID!): Boolean!
}

// Resolver

Mutation: {
  // ...existing createPost, updatePost resolvers...
  deletePost: (parent, args, context) => {
    return db.posts.delete(args.id); // returns true/false depending on success
  },
}

WHY THIS PARTICULAR MUTATION REASONABLY RETURNS A BOOLEAN
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After a successful delete, the object no longer exists — there is
nothing left to query fields FROM, so returning the deleted Post itself
(as createPost and updatePost do) isn't meaningfully possible the way it
is for a create or update, where the object still exists afterward for
the client to immediately query further details from in the same round
trip.

WHY THIS WORKS
--------------
- id: ID! is taken directly as a plain scalar argument here, rather than
  wrapped in an input type — this is a legitimate and common exception:
  input types exist to group multiple related arguments together
  cleanly, but a mutation needing only a single simple scalar argument
  (like "which ID to delete") doesn't gain anything from being wrapped
  in a dedicated input type just for the sake of consistency.
- Returning Boolean! (rather than a nullable Boolean) is deliberate: the
  mutation should always be able to report definitively whether the
  delete succeeded or not — there's no legitimate "unknown" outcome
  state for a delete operation the way there might be for some other
  more ambiguous operations.
- This is exactly the "few reasonable cases" the challenge alludes to:
  the general convention from the chapter (return the affected object)
  exists specifically so a client can immediately query further data
  about what it just created or changed — a convention that simply
  doesn't apply once the underlying object has been removed entirely.