nc_define_modules       Define co-occurrence modules
nc_eval                 Compute co-occurrence probabilities
nc_occ_probs            Compute the occurrence probabilities
nc_occ_probs_simple     Compute the occurrence probabilities
nc_randomize            Randomize the occurrence matrix
nc_randomize_R          Randomize the occurrence matrix
nc_randomize_fast       Randomize the occurrence matrix
nc_randomize_simple     Randomize the occurrence matrix
safe_sample             Sample one item from a vector, even when the
                        vector has length 1
