Split the thousands

Problem

"Is that twelve thousand or one million two hundred thousand?" the boatswain grumbles over the treasure ledger. So he stops getting lost, the captain wants every haul written down with commas.

Write a function that takes a whole number from 0 up and returns a string with its digits and a comma every three, counting from the right: 1234567 is written "1,234,567" and 45678 is written "45,678".

A number with three digits or fewer gets no comma: 999 stays "999" and 0 stays "0". A comma never goes at the start: 300000 is "300,000". And the zeros in each group are all written: 5007 is "5,007".

Examples

• A million and change

  1234567 → "1,234,567"

• Three digits

  999 → "999"

• The first thousand

  1000 → "1,000"

• Short group in front

  45678 → "45,678"

• A huge haul

  250000000 → "250,000,000"

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

You start with this

def with_commas(n):
    pass

function withCommas(n) {
}