ket fn: to-upper

to-upper:
    description:
        to-upper ket
        set all characters to upper case

        to-upper[i1, i2, ..., in] ket
        change i'th characters to upper case

    examples:
        to-upper |fred>
            |FRED>

        to-upper[1] |fred>
            |Fred>

        to-upper[1,3,5] |abcdefg>
            |AbCdEfg>

    see also:
        to-lower