declare function fn(x: any): void;
declare function takeTwo(x: any, y: any): void;
declare function withRest(a: any, ...args: Array<any>): void;
var n: number[];

fn(1) // no error
fn(1, 2, 3, 4)
takeTwo(1, 2, 3, 4)
withRest('a', ...n); // no error
withRest();
withRest(...n);