src/ansi_to_html.js
function toHexString(num) {
    var str = num.toString(16);

    while (str.length < 2) {
        str = '0' + str;
    }

    return str;
}
function toHexString(num) {
    var str = num.toString(16);

    while (str.length < 2) {
        str = '0' + str;
    }

    return str;
}
Converts from a number like 15 to a hex string like 'F'
@param {number} num
@returns {string}