clarification on output
Hi,

On using bert_uncased on the following sentence:

`Hello this is my dog`

and to get attentions I use:

`last_hidden_states, pooler_outputs, hidden_states, attentions = outputs`

`attentions` gives:
a tuple of 12 tensors where each tensor is of size [1,12,5,5]

I was wondering if the 12 tensors in the tuple are for each attention head or hidden layer.

Thanks!