import torch
from torch._six import with_metaclass


class VariableMeta(type):
    def __instancecheck__(cls, other):
        return isinstance(other, torch.Tensor)


# mypy doesn't understand torch._six.with_metaclass
class Variable(with_metaclass(VariableMeta, torch._C._LegacyVariableBase)):  # type: ignore
    pass


from torch._C import _ImperativeEngine as ImperativeEngine
Variable._execution_engine = ImperativeEngine()  # type: ignore