// Inline add and addR
def sum(ns: Int*): Int = ns.foldLeft(0)((n, m) => n + m) // inlined add
scala> sum(33, 42, 99)
res2: Int = 174 // alright
def sumR(ns: Int*): Int = ns.foldLeft(0)((n, m) => return n + m) // inlined addR
scala> sumR(33, 42, 99)
res3: ???
What will this expression return and why?