The game Prongle is played with a special deck of cards: on each card is a nonempty set of distinct colors. No two cards in the deck contain the exact same set of colors. In this game, a “Prongle” is a set of at least 2 cards such that each color is on an even number of cards in the set. Let k be the maximum possible number of prongles in a set of 2019 cards. Find \left\lfloor\log _{2}(k)\right\rfloor.