Returns a tensor with all the dimensions of input of size 1 removed.
For example, if input is of shape:
\((A \times 1 \times B \times C \times 1 \times D)\) then the out tensor
will be of shape: \((A \times B \times C \times D)\).
When dim is given, a squeeze operation is done only in the given
dimension. If input is of shape: \((A \times 1 \times B)\),
squeeze(input, 0) leaves the tensor unchanged, but squeeze(input, 1)
will squeeze the tensor to the shape \((A \times B)\).