def __init__(self, assets_dir=None, requirements_file="requirements.yml"):
        self.assets_dir = assets_dir or Path(".") / "assets"
        self.requirements = GroupedRequirements()
        self.requirements.load(requirements_file)
        self.temp_dir = mkdtemp()
def _get(delta, start):
            p = start
            while delta:
                p = p.next
                delta -= 1
            return p.val