bill_brackets = {
const lowestbill = billionaire_incomes[billionaire_incomes.length-1];
const lowest_index = d3.bisect(brackets, lowestbill) - 1;
const brackets_bill = brackets.slice(lowest_index);
const brackets_count = brackets_bill.map(e => ({ x: e, y: 0 }));
for (let inc of billionaire_incomes) {
let i = d3.bisect(brackets_bill, inc);
brackets_count[i-1].y = 1;
}
return brackets_count.filter(e => e.y != 0);
}