code: public static boolean sanityCheck(int flags) {
  		doCheck(flags, ConformanceFlags.CHECKED | ConformanceFlags.UNCHECKED);
  		if ((flags & ConformanceFlags.UNCHECKED) == 0) {
  			doCheck(flags, ConformanceFlags.CHECK_RESULTS);
  		} else if ((flags & (ConformanceFlags.SEALED | ConformanceFlags.CHECK_RESULTS)) != 0) {
  			throw new IllegalArgumentException("Invalid flags: " + toString(flags));
  		}
  		return true;
  	}
docs: Simple sanity check for the given flags.
  
  Returns always {@code true} such that it can be used in Java assertions.
  Will throw an {@link IllegalArgumentException} if the flags appear to be bogus.