----------  baseline  ----------
$ python -m timeit -s "from collections import deque" -s "s = list(range(10000))" "9000 in s"
10000 loops, best of 3: 102 usec per loop
$ python -m timeit -s "from collections import deque" -s "s = deque(range(10000))" "9000 in s"
10000 loops, best of 3: 130 usec per loop
$ python -m timeit -s "from collections import deque" -s "s = list(range(10000))" "9000 in s"
10000 loops, best of 3: 101 usec per loop
$ python -m timeit -s "from collections import deque" -s "s = deque(range(10000))" "9000 in s"
10000 loops, best of 3: 130 usec per loop

--------- deque_contains.diff -------
$ python -m timeit -s "from collections import deque" -s "s = list(range(10000))" "9000 in s"
10000 loops, best of 3: 101 usec per loop
$ python -m timeit -s "from collections import deque" -s "s = deque(range(10000))" "9000 in s"
10000 loops, best of 3: 103 usec per loop
$ python -m timeit -s "from collections import deque" -s "s = list(range(10000))" "9000 in s"
10000 loops, best of 3: 100 usec per loop
$ python -m timeit -s "from collections import deque" -s "s = deque(range(10000))" "9000 in s"
10000 loops, best of 3: 103 usec per loop