mathjs/lib/esm/plain/bignumber/index.js

import Decimal from 'decimal.js';
export * from './arithmetic.js'; // TODO: this is ugly. Instead, be able to pass your own isBigNumber function to typed?

var BigNumber = Decimal.clone();
BigNumber.prototype.isBigNumber = true;
export function bignumber(x) {
  return new BigNumber(x);
}