Set union doesn’t require `inout`.
Set union doesn’t require `inout`.

robrix/Set,madbat/Set,IngmarStein/Set,madbat/Set,madbat/Set,robrix/Set,IngmarStein/Set,natecook1000/Set,robrix/Set,IngmarStein/Set,natecook1000/Set,natecook1000/Set