Describe how to use the occupation fraction in the user guide. In detail, ab initio every galaxy is assumed to have MBH. This assumption can be alleviated by "weighting" by the occupation fraction focc = focc(Mstar). For each galaxy, we should provide a column e.g. "has_bh", which can be defined as has_bh = U < focc(Mstar) where U is a uniform random variable between 0 and 1. Then, in any calculation using MBH, one can then weight by "has_bh" in order to account for an occupation fraction less than unity. For AGN, the logic remains the same, i.e. one can weight by is_agn \times has_bh for any calculation.