DList.removeBack

DList!int l;

l.insertFront(8);
l.insertFront(9);
assert(l.front == 9);
l.removeFront();
assert(l.front == 8);
l.removeFront();
assert(l.empty);

auto l = DList!int([9, 8]);

assert(l.back == 8);
l.removeBack();
assert(l.back == 9);
l.removeFront();
assert(l.empty);