Thanks, Erik. I'm afraid that I'm not a native English spearker, so
sometimes it's not easy to express my own idea in exact English
expression.

Of course, I did look up the reference and found what instance_eval
does when being called. What I tried to ask was, as you stated,
"If we can do this, what's the purpose of 'protected' or 'private'?"

Thanks in advance.

Best,
Minkoo Seo