Couple examples of yield

yield.rb

# yield is like "do the thing that is in the block"

def do_twice
  yield
  puts "again!"
  yield
end

do_twice { puts "hello world" }
do_twice do
  puts "same thing, multiline syntax"
end

def times_two
  2 * yield
end

times_two { 3 + 5 } # will return 16 (8*2)
times_two { 5 + 1 } # will return 12 (6*2)