Settings with Index

Sometimes you don’t know property names in advance. An index signature says: any string key is allowed, and its value has one of a few types. This is useful for settings, flags, or small dictionaries.

interface Flags {
  [key: string]: boolean;
}

You will count how many settings are turned on.

Your Task

Count enabled flags in a settings object.

Define interface Settings { [key: string]: string | number | boolean }.
Implement countEnabled(s: Settings): number that returns how many values are exactly true.
Return 0 when the object has no keys.
Do not mutate the input.