Link objects are references to filesystem links.
Future<Link>
that completes with
the link when it has been created. If the link exists,
the future will complete with an error. [...]
Future<Link>
that completes
with a Link instance for the renamed link. [...]
Future<Link>
that completes with the
link when it has been updated. Calling update on a non-existing link
will complete its returned future with an exception.
Future<bool>
that completes with the result. [...]