Memoize with a begin block

memoize.rb

def expensive_stats(id)
  @expensive_stats ||= []

  @expensive_stats[id] ||= begin
    puts "Executing resource intensive method for ID: #{id}"
    sleep 5
    Time.now
  end
end

puts expensive_stats 3
puts expensive_stats 3
puts expensive_stats 3

puts expensive_stats 7
puts expensive_stats 7
puts expensive_stats 7