code: def rpc_get_zonefile_inventory( self, offset, length, **con_info ):
          
          conf = get_blockstack_opts()
          if not is_atlas_enabled(conf):
              return {'error': 'Not an atlas node', 'http_status': 400}
  
          if not check_offset(offset):
              return {'error': 'invalid offset', 'http_status': 400}
  
          if not check_count(length, 524288):
              return {'error': 'invalid length', 'http_status': 400}
  
          zonefile_inv = atlas_get_zonefile_inventory( offset=offset, length=length )
  
          if BLOCKSTACK_TEST:
              log.debug("Zonefile inventory is '%s'" % (atlas_inventory_to_string(zonefile_inv)))
  
          return self.success_response( {'inv': base64.b64encode(zonefile_inv) } )
docs: Get an inventory bit vector for the zonefiles in the
          given bit range (i.e. offset and length are in bytes)
          Returns at most 64k of inventory (or 524288 bits)
          Return {'status': True, 'inv': ...} on success, where 'inv' is a b64-encoded bit vector string
          Return {'error': ...} on error.