Creating Mapped Types

type Album = {
	title: string
	year: number
}

type Optional<T> = { [K in keyof T]?: T[K] }
type OptionalAlbum = Optional<Album>

1. MyPartial<T> — every property optional
2. MyRequired<T> — every property required (optional markers removed)
3. Nullable<T> — every property becomes Original | null
4. Mutable<T> — every readonly property becomes writable
5. Stringify<T> — every property becomes string

• partial: { name: 'Alice' }
• nullable: { id: null, name: 'Bob', email: null, age: 30 }
• mutable: a full writable user object where mutable.name = 'Updated' type-checks