This processor allows calculations to be done on each element of a collection or object.
colletion or object to process.input element, the array/object key is stored in VarTemporary under this key string.input element, the array/object value is stored in VarTemporary under this key string.input, item_key_key, item_val_key are pre-calculated.
Each element in input is fetched in turn, stored as a VarTemporary (using <for_each_item id>.key and <for_each_item id>.key keys), and process_loop is run.
Once each element has been processed, if there is any logic to run in process_after, then that logic will be processed.