public Extent minus(Extent byteSize) throws UninterruptibleNoWarnPragma {
public Extent minus(int byteSize) throws UninterruptibleNoWarnPragma {
  public Extent minus(Extent byteSize) throws UninterruptibleNoWarnPragma {    if (VM.VerifyAssertions && VM.runningVM) VM._assert(VM.NOT_REACHED);    return new Extent(value - byteSize.value);  }