What every supplier carries

Problem

Don Ramiro stocks his hardware store from several suppliers, and each one leaves him a catalog. Before placing the order he wants to see which items he can buy from any of them: those are the ones that will never be missing from the counter.

Write a function that takes catalogs, a list where each element is one supplier's catalog: a list of items written in lowercase and with no accents. A catalog may repeat an item and may come empty. Return the list of the items that are in every catalog, in alphabetical order and with no repeats.

With three catalogs, ["tape", "hammer", "nail"], ["nail", "tape", "brush"] and ["tape", "nail", "drill"], the nail and the tape are in all three, and the hammer, the brush and the drill are in only one: you return ["nail", "tape"].

If no item is in every catalog, or if no catalog arrived at all, you return an empty list.

Examples

• The example

  [["tape", "hammer", "nail"], ["nail", "tape", "brush"], ["tape", "nail", "drill"]] → ["nail", "tape"]

• Nothing in common

  [["nail", "sandpaper"], ["brush", "cable"]] → []

• A single catalog

  [["drill", "brush", "drill"]] → ["brush", "drill"]

• An item repeated in the same catalog

  [["tape", "tape", "nail"], ["nail", "tape"]] → ["nail", "tape"]

Besides these, the challenge has hidden tests that are revealed when you submit your solution.

You start with this

def common_stock(catalogs):
    pass

function commonStock(catalogs) {
}