forked from Mirror/wren
The methods Sequence.map and Sequence.where are now implemented using deferred execution. They return an instance of a new Sequence-derived class that performs the operation while iterating. This has three main advantages: * It can be computationally cheaper when not the whole sequence is iterated. * It consumes less memory since it does not store the result in a newly allocated list. * They can work on infinite sequences. Some disadvantages are: * Iterating the returned iterator will be slightly slower due to the added indirection. * You should be aware that modifications made to the original sequence will affect the returned sequence. * If you need the result in a list, you now need to call Sequence.list on the result.