code: public static boolean hasLevel( ASpatialDb db, int levelNum ) throws Exception {
          String tablename = TABLENAME + levelNum;
          return db.hasTable(tablename);
      }
docs: Checks if the given level table exists.
  
  @param db the database.
  @param levelNum the level number to check.
  @return <code>true</code> if the level table exists.
  @throws Exception