properties() and propertyNames()

[koraa]

const propertyNames = (o) => {
  for (const k in o) yield k;
};

const properties = (o) => {
  for (const k in o) yield (k, k[o]);
};

This would be useful e.g. for lazy iteration over process.env.

[koraa]

(this is basically turns for…in into a sequence)

[koraa]

Superseeded by #182.