[Users] Reduction in slices?

Dear all,

Assume I have a thorn mounted on Carpet, completely unrelated to any GR thorn (say my_wavetoy) .

Is there a way to estimate the integral of a grid function on every slice of z=constant?

This reminds me the outflow thorn that is capable of estimating the integral of fluxes (grid functions) across a spherical surface.

I wonder whether there is something similar to integrate a flux (a given grid function of my choice) across z=constant planes:

- perhaps a reduction operator from Carpet - a similar thorn to outflow

Thanks in advance, Francisco