exit status: 1 with stderr:
<stdin>:1:12: warning: when calling this function in Swift 4 or later, you must pass a '()' tuple; did you mean for the input type to be '()'? func f( a: (Void) -> Void...) { } ^~~~~~ () <stdin>:2:3: error: extra arguments at positions #2, #2 in call f {} _: {} ^ <stdin>:1:6: note: 'f(a:)' declared here func f( a: (Void) -> Void...) { } ^