public boolean compareAndSet(final long expectedValue,final long newValue){
  return UNSAFE.compareAndSwapLong(this,VALUE_OFFSET,expectedValue,newValue);
}

public boolean compareAndSet ( final long expectedValue , final long newValue ) { return UNSAFE . compareAndSwapLong ( this , VALUE_OFFSET , expectedValue , newValue ) ; }
perform a compare and set operation on the sequence .
