code: def index(self, block_start, block_end):
          
          log.debug("BEGIN Processing zonefiles discovered since last re-indexing")
          t1 = time.time()
          self.index_discovered_zonefiles(block_end)
          t2 = time.time()
          log.debug("END Processing zonefiles discovered since last re-indexing ({} seconds)".format(t2 - t1))
docs: Entry point for indexing:
          * scan the blockchain from start_block to end_block and make sure we're up-to-date
          * process any newly-arrived zone files and re-index the affected subdomains