format pp_simp_extensions_for_head(priority_queue<simp_ext_record, simp_ext_record_cmp> const & q) { format fmt; q.for_each([&](simp_ext_record const & r) { fmt += format(r.m_ext_name); unsigned prio = *q.get_prio(r); if (prio != LEAN_DEFAULT_PRIORITY) fmt += space() + paren(format(prio)); fmt += line(); }); return fmt; }