[cctbxbb] mask calculation using mmtbx

Hi, I am trying to use the cctbx to calclate a mask given a pdb following the exemple given on a newsletter. I am using a windows version of the cctbx extracted from the bundle. But in the exemple, the mask is constructed using the masks.mask_utils function from mmtbx. But I cannot see this function in mmtbx.masks. Is there another function I can use to construct a solvent mask? Thanks for any help Celine Besnard