fem_tutos/node_modules/d3-array/src/superset.js

export default function superset(values, other) {
  const iterator = values[Symbol.iterator](), set = new Set();
  for (const o of other) {
    const io = intern(o);
    if (set.has(io)) continue;
    let value, done;
    while (({value, done} = iterator.next())) {
      if (done) return false;
      const ivalue = intern(value);
      set.add(ivalue);
      if (Object.is(io, ivalue)) break;
    }
  }
  return true;
}

function intern(value) {
  return value !== null && typeof value === "object" ? value.valueOf() : value;
}