func closure(_ f1: () -> Void) -> (() -> Void) -> Void {

	return { f2 in f1(); f2() }
}

// Store and call
let f2 = closure { print("A") }
f2 { print("B") }

// Trailing Closure + Parameter
closure { print("C") } ({ print("D") })

// Parameter + Parameter
closure({ print("C") })({ print("D") })

// Trailing Closure + Trailing Closure
// NG: extra argument in call
//closure { print("C") } { print("D") }