How to get the current characteristic value inside the on_write callback?

[ChocolateLoverRaj]

I have a characteristic and I want to run some code on on_write only if the new value is different than the current value. However, I can't access the current value inside the on_write callback. Is there a better solution than storing another copy of the value outside the characteristic?

[taks]

I have added current_data to OnWriteArgs.
Please check.