Write PathKeys<T>: every dot path into a nested object, like "account.address.city".
PathKeys<T> is the union of every path to a property of T: each top-level key, and for each property whose value is an object, that key, a dot, and each path inside it. Treat arrays as leaves, so there are no paths into them. An optional object property still has its paths. A type that refers to itself, like a linked list, must not break the compiler: stop after 5 levels.
type PathKeys<T> = keyof T; // type Settings = { theme: string; account: { email: string; address?: { city: string } } };// PathKeys<Settings>// // "theme" | "account" | "account.email" | "account.address" | "account.address.city"The answer
Write it yourself first. Then compare it with a reference solution and the checks it passes.
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