SList: How do I use linearRemove?

[Lemonfiend via Digitalmars-d-learn]

> linearRemove is linear, so I think it accepts a range. Perhaps 
> the "once" range is enough.
I cannot find once in the docs. Did you mean std.range.only?

Error: function std.container.SList!(Tree).SList.linearRemove 
(Range r) is not callable using argument types (OnlyResult!(Tree, 
1u))