code: public static short getMagicNumber(Class clazz) {
          Short i=classMap.get(clazz);
          if(i == null)
              return -1;
          else
              return i;
      }
docs: Returns the magic number for the class.
  
  @param clazz a class object that we want the magic number for
  @return the magic number for a class, -1 if no mapping is available