You are given the chance of demonstrating you front-end skills by creating a "mind-reading" magic trick!  The trick consists of arranging a deck of 21 cards into three piles of seven cards each, the user should be asked to pick a card and tell the pile on which the chosen card is contained. You should now rearrange the cards into three new piles, always keeping the pile that was appointed by the user in the middle of the other two. This process is repeated two more times (making a total of 3 rounds), after that, if the piles were correctly arranged in every round, the card that was picked by the user, in the beginning, will be placed in the middle of the deck (11th card).