gistfile1.rb

require 'parallel'

def with_gear_rotation(options={}, &block)
  gears = [1,2,3]
  parallel_output = Parallel.map(gears, :in_threads => 3) do |target|
    rotate_and_yield(target, options, &block)
  end
end

def rotate_and_yield(target, options, &block)
  out = []
  out << "Rotate out #{target}"
  out << yield(target, options)
  out << "Rotate in #{target}"
  out
end

def restart(options={})
  with_gear_rotation do |target, options|
    restart_gear(target, options)
  end
end

def restart_gear(target, options)
  "restart_gear #{target}"
end

output = restart
output.each do |o|
  puts o.join("\n")
  puts ""
end

gistfile2.txt

Rotate out 1
restart_gear 1
Rotate in 1

Rotate out 2
restart_gear 2
Rotate in 2

Rotate out 3
restart_gear 3
Rotate in 3