Split the logic: write `isValidAddress(a)` (starts with `0x`, 42 chars) and `normalize(a)` (lowercased) and `clean(a)` using both, returning `null` when invalid.
Required in your answer: startsWithtoLowerCase
Runs in a sandboxed worker
function isValidAddress(a) {
// TODO
}
function normalize(a) {
// TODO
}
function clean(a) {
// TODO
}
