Coroutines memory lookups - Permit multi memory lookups inside coroutines.
test tests::basic_110_256mb ... bench: 16,369 ns/iter (+/- 3,438)
test tests::basic_one_256mb ... bench: 21 ns/iter (+/- 2)
test tests::gen_110_256mb ... bench: 15,941 ns/iter (+/- 2,305)
test tests::gen_one_256mb ... bench: 65 ns/iter (+/- 7)