not

assert (not (false));
assert (not!false);

auto a = false;

assert (not (a));
assert (not!a);

enum b = false;
assert (not (b));
assert (not!b);

auto c () {return false;}

assert (not (c));
assert (not!c);

auto d (int x){return x == 1;}

assert (not (d(0)));
assert (not!d (0));

alias e = not!d;

assert (e(0));
assert (not!e (1));

assert (not!(x => x % 2 == 0)(1));