Addl methods?

Could add keys, values, and/or forEach methods... but the problem is whether or not to include the "stale" (prev) cache values. These are technically on their way out & not necessarily current values, but may be. 🤔

Since a LRU is really just a set and get anyway, this may fall out of scope anyway.

Could also add a remove method, but it still falls out of scope. At least it doesn't have the same stale-vs-not concern.

Extracted snippet before release. Removing methods is breaking, but adding them is not~

remove: function (key) {
  if (curr[key] !== void 0) {
    curr[key] = void 0;
  }
  if (prev[key] !== void 0) {
    prev[key] = void 0;
  }
},
keys: function () {
  var k, arr=[];
  for (k in curr) arr.push(k);
  return arr;
},
values: function () {
  var k, arr=[];
  for (k in curr) arr.push(curr[k]);
  return arr;
},
forEach: function (fn, ctx) {
  ctx = ctx || this;
  for (var k in curr) {
    fn.call(ctx, curr[k], k, curr);
  }
}

The issue does not name a file or test; start by locating the LRU implementation and tracing how the curr and prev caches are maintained. Confirm the supported method scope and stale-value semantics with maintainers, then add coverage for the agreed behavior.