Once there was a little bunny and a little unicorn.

They were gambading in the campaign when suddenly a grizzlybear appeared right before their weary eyes.

• But what do you want, oh grizzlybear? asked the little bunny
• Thy shall not use foreach! said the grizzlybear.
• But, replied the unicorn, but what else is there?
• Recursion is your only hope, the grizzlybear affirmed.

Strengthened by their new knowledge, the little bunny and the little unicorn went back to their starting point and tried all over again.

• This time, claimed the little bunny, we will think before writing
• This time, shouted the unicorn, we will use interfaces and closures
• Yes, this time, truly the core will be a place full of wonder and amazement
• Let's go for it!

And this is the way their journey begun.