forEach (cb, thisArg) {
    this.index.visitAll(cb, thisArg)
  }
Iterate over all records.

@example
collection.forEach(function (record) {
  // do something
});

@method Collection#forEach
@since 3.0.0
@param {Function} forEachFn Iteration function.
@param {*} [thisArg] Context to which to bind `forEachFn`.
@returns {Array} The result.