Interpolation along particular axis

Currently, the interpolation function performs the interpolation along the 0th and the 1st axis. However, in my problem of interest, I need to interpolate along all the 4 axes. Could the feature of having interpolation along a particular axis be added on in `af.approx2`. Right now, I'm reordering the arrays such that the axes along which I need to interpolate are moved to the 0th and 1st axes. After which I need to reorder the resulting array to bring it back to the original convention.

This is what I'm currently doing right now:
```python
# vel_y_interpolant is stacked along axis 2
# vel_x_interpolant is stacked along axis 3
f_interp = af.approx2(af.reorder(f, 2, 3, 0, 1),\
af.reorder(vel_y_interpolant, 2, 3, 0, 1),\
af.reorder(vel_x_interpolant, 2, 3, 0, 1),\
af.INTERP.BICUBIC_SPLINE
)

f_interp = af.reorder(f_interp, 2, 3, 0, 1)
```