1. Let _iterator_ be the **this** value.
Is it possible to indicate the spec reader, that the iterator variable will not change in the following algorithm?
1. Let const _iterator_ to be the **this** value.
Immutable constants can reduce the reading effort. (Also need support from the linter to ban the re-assignment on the const variable, and the spec render to mark it visually different from the
let which is mutable).