Function dstack 

pub fn dstack<T: Element>(
    arrays: &[Array<T, IxDyn>],
) -> FerrayResult<Array<T, IxDyn>>

Stack arrays along the third axis (depth-wise).

For 1-D arrays of shape (N,), reshapes to (1, N, 1). For 2-D arrays of shape (M, N), reshapes to (M, N, 1). Then concatenates along axis 2.

Analogous to numpy.dstack().