transfers = {
const x = new Map()
for (const alias of aliases) {
x.set(alias, 0);
}
for (const {from, to, amount} of transferRecords) {
const fromBal = x.get(from) || 0;
const toBal = x.get(to) || 0;
x.set(from, fromBal - amount);
x.set(to, toBal + amount);
}
return x;
}