"""Small tensor container for the upstream video reward's batch-only API."""
class TensorBatch:
    def __init__(self,batch,meta_info=None):
        self.batch=batch
        self.meta_info=meta_info or {}
    @classmethod
    def from_single_dict(cls,batch,meta_info=None):return cls(batch,meta_info)
    def __len__(self):return len(next(iter(self.batch.values())))
    def __getitem__(self,index):return type(self)({k:v[index] for k,v in self.batch.items()},self.meta_info)