'use strict';


export function create(obj, proto=Object.prototype) {
  const props = Object.keys(obj)
    .map((key) => [ key, { value: obj[key], enumerable: true } ])
    .reduce((acc, [ key, value ]) => ({ ...acc, [key]: value }), {});

  return Object.create(proto, props);
};


export function random_choice(collection, r) {
  const idx = Math.floor(collection.length * r);
  return collection[idx];
}


export function pairs(arr1, arr2) {
  return arr1
    .map((x, i) => arr2.map(y => [x, y]))
    .flat();
}