toDelegate
fn
auto toDelegate(Set)(Set set) if (isCodepointSet!Set)Builds a Trie with typically optimal speed-size trade-off
and wraps it into a delegate of the following type:
bool delegate(dchar ch).
Effectively this creates a 'tester' lambda suitable
for algorithms like std.algorithm.find that take unary predicates.
See the Synopsis, Synopsis section for example.