Constructable

A type which describes a function which would return an instance of a class Typically, we call this the "new" method in a language. A sample usage: ```ts class MyClass { readonly myProp: string = 'prop'; name: string; constructor(name: string){ this.name = name; } } const map = { "key": Myclass } let instance = new map["key"]; instance instanceof MyClass //true ```