[cctbxbb] electron density value near an atom

Dear CCTBX users/developers I would like to calculate the theoretical electron density value at a point in space as a function of an atom specified by its coordinate and its form factor. I’ll assume it’s for a certain X-ray wavelength, say 1.0Å. If someone would have the time to give me a few pointers on how to do this using the CCTBX I'd be very grateful. Thanks in advance, Rob