The last four

Problem

A receipt never shows the whole card: only its last four digits. Write a function that takes the card number as text and returns those last four: with "4539123456789012" you return "9012".

The answer is text, not a number, so a leading zero stays. And if the card has four digits or fewer, you return all of it.

Examples

• "4539123456789012" → "9012"

• Starting with a zero

  "987650012" → "0012"

• Exactly four

  "5555" → "5555"

• "12345" → "2345"

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

You start with this

def last_four(card):
    pass

function lastFour(card) {
}