.mixin (...) { // matches 0-N arguments
.mixin () { // matches exactly 0 arguments
.mixin (@a: 1) { // matches 0-1 arguments
.mixin (@a: 1, ...) { // matches 0-N arguments
.mixin (@a, ...) { // matches 1-N arguments
Furthermore:
.mixin (@a, @rest...) {
// @rest is bound to arguments after @a
// @arguments is bound to all arguments
}
This is a GREAT change, @cloudhead. Thanks!