seeding
Initial HPV-prevalence curves and multi-genotype seeding Connector.
The age-banded init_prev curves and _make_init_prev_fn sampler are used by both per-genotype HPV modules (for init_seeding='independent') and by _ExclusiveSeeder (for init_seeding='exclusive', which uses the ‘total’ curve as the any-HPV Bernoulli before genotype assignment).