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 dfs(self,can,cursum,target,res):
        if cursum > target: return 
        if cursum == target: 
            self.result.append(res)
            return 
        for i in xrange(len(can)):
            if not res or res[len(res)-1] <= can[i]:
                self.dfs(can,cursum+can[i],target,res+[can[i]])