Tuple
Code
var someTuple = (top: 10, bottom: 12) // someTuple is of type (top: Int, bottom: Int)
someTuple = (top: 4, bottom: 42) // OK: names match
someTuple = (9, 99) // OK: names are inferred
someTuple = (left: 5, right: 5) // Error: names don't match