sub Mojo::IOLoop::Delay::cb {
    my ($self, $cb) = @_;
    my $end = $self->begin(0);
    return sub { $end->( $cb->(@_) ) };
}

for my $i (1 .. 10) {
  ## my $end = $delay->begin;
  ## Mojo::IOLoop->timer($i => sub {
  Mojo::IOLoop->timer($i => $delay->cb(sub {
    say 10 - $i;
    ## $end->();
  ## });
  }));
}