number of non-heavy atoms

Something really simple, PP (6.1) should be able to do it, yet I haven't found out how: I want to filter for molecules with explicit non-heavy atoms.

For hydrogen atoms this is easy: num_explicithydrogens will tell me the number (and they are easily removed with "Remove Hydrogens" component). However, what about deuterium, R/X/Z/* "atoms" etc? What I was searching for but could not find is an num_all_atoms function: the number of atoms present including hydrogen, deuterium, R/X/Z/* etc. The num_atoms function gives me the number of heavy atomns, so if (num_all_atoms - num_atoms > 0) I know I have one of those molecules that need special treatment (a remove_non_heavy_atoms component/function would go a long way towards the latter).

Cheers,