Profile a code block

profile.rb

# returns number of seconds elapsed on average for block execution
def profile(num_times, idx, &block)
  profile_arr = []
  num_times.times do
    beginning = Time.now
    block.call(idx)
    idx+=1
    profile_arr << Time.now - beginning
  end
  profile_arr.reduce(:+).to_f / profile_arr.size
end