gistfile1.txt

t1 = Thread.new {
  c = 'a'
  25.times { print c.next!;sleep 1 }
}

t2 = Thread.new {
  25.times { |i| print i;sleep 1 }
}

t1.join
t2.join

Produces: b01cd2e34fg5h6i7j8k9l10m11n12o13p14q15r1617s18t19u20v21w22x23y24z

t1 = Thread.new {
  c = 'a'
  25.times { print c.next!;sleep 1 }
}.join

t2 = Thread.new {
  25.times { |i| print i;sleep 1 }
}.join

Produces: bcdefghijklmnopqrstuvwxyz0123456789101112131415161718192021222324