The axis or axes along which to perform the reduction.
axis=(), will compute over all elements into a
scalar array with shape
axis is int, a reduction is performed on a particular axis.
axis is a tuple of ints, a reduction is performed on all the axes
specified in the tuple.
exclude is true, reduction will be performed on the axes that are
NOT in axis instead.
Negative values means indexing from right to left.
Whether to perform reduction on axis that are NOT in axis instead.
If this is set to
True, the reduced axes are left in the result as dimension with size one.