promise_resolve: Create a resolved or rejected promise
Description
Helper functions to conveniently create a promise that is resolved to the
given value (or rejected with the given reason).
Usage
promise_resolve(value)
promise_reject(reason)
Arguments
value
A value, or promise, that the new promise should be resolved to.
This expression will be lazily evaluated, and if evaluating the expression
raises an error, then the new promise will be rejected with that error as
the reason.