in lib/h3core.js [252:263]
function hexFrom32Bit(num) {
if (num >= 0) {
return num.toString(BASE_16);
}
// Handle negative numbers
num = num & 0x7fffffff;
let tempStr = zeroPad(8, num.toString(BASE_16));
const topNum = (parseInt(tempStr[0], BASE_16) + 8).toString(BASE_16);
tempStr = topNum + tempStr.substring(1);
return tempStr;
}