Why does this assignment operation of Variable not work?

1 
a = Variable(torch.FloatTensor([1,1]))
a[0].data = torch.FloatTensor([2])
print(a[0])   # doesn't work, it is still [1], not [2]
2

OK, I know that.
It should be
a.data[0] = 2

3

If you want backprop, avoid using .data on Variable.