gather.pl

  # Synchronize multiple events
  my $delay = Mojo::IOLoop->delay(sub { say 'BOOM!' });
  for my $i (1 .. 10) {
    my $cb = $delay->gather;
    Mojo::IOLoop->timer($i => sub {
      say 10 - $i;
      $cb->();
    });
  }
  $delay->wait;

  # Sequentialize multiple events
  Mojo::IOLoop->delay(

    # First step (simple timer)
    sub {
      my $delay = shift;
      Mojo::IOLoop->timer(2 => $delay->gather);
      say 'Second step in 2 seconds.';
    },

    # Second step (concurrent timers)
    sub {
      my $delay = shift;
      Mojo::IOLoop->timer(1 => $delay->gather);
      Mojo::IOLoop->timer(3 => $delay->gather);
      say 'Third step in 3 seconds.';
    },

    # Third step (the end)
    sub { say 'And done after 5 seconds total.' }
  )->wait;