ket fn: to-comma-number

to-comma-number:
    description:
        to-comma-number ket
        insert thousands commas into numbers

    examples:
        to-comma-number |8825>
            |8,825>

        to-comma-number |population: 2300000>
            |population: 2,300,000>

        to-comma-number |km: 22956.53>
            |km: 22,956.53>

    see also:
        table, round