def coerce(cls, string):
        """Create a :class:`Requirement` object from a given package spec."""
        match = re.match(cls.spec_regex, string)
        if not match:
            raise InvalidRequirementSpecError("could not parse requirement")
        package = match.group(1)
        if all(match.group(2, 3)):
            version = "".join(match.group(2, 3))
        else:
            version = None
        return cls(package, version)
def test():
    start = time.time()
    treap = None
    s = set()
    for i in range(100000):
        key = random.randint(0, 10000)
        if random.randint(0, 1) == 0:
            if key in s:
                treap = remove(treap, key)
                s.remove(key)
        elif key not in s:
            treap = insert(treap, key)
            s.add(key)
        assert len(s) == size(treap)

    for i in range(size(treap)):
        assert kth(treap, i) in s
    print(time.time() - start)