Torch.as_tensor not available in TorchScript

I am trying to convert a list of tuples into a tensor using torch.as_tensor which throws the following error:

unknown builtin op: aten::as_tensor
Could not find any similar ops to aten::as_tensor. This op may not exist or may not be currently supported in TorchScript

Is there any other way to accomplish this? Using torch.tensor also doesn’t work.
I’m using PyTorch version 1.1.0