8.20.3 Can you answer these questions?

8.20.3.1 how does the nested \def in \def\inst \beamer@insttitle \def\and \beamer@andtitle

https://tex.stackexchange.com/landing/r/digest?cta=question&id=637631

I am trying to understand the following code: 
\def\author{\@dblarg\beamer@author} 
\long\def\beamer@author[#1]#2{% 
\def\insertauthor{\def\inst{\beamer@insttitle}\def\and{\beamer@andtitle}#2}% 
} 
... 
[macros] [code] [package-writing] [documentclass-writing]
 

asked by el_tenedor https://tex.stackexchange.com/landing/r/digest?cta=user&id=133604 Score of 1

8.20.3.2 weird verbatim-like manual environment writing with luatex preprocessing

https://tex.stackexchange.com/landing/r/digest?cta=question&id=637555

I'm currently trying to make my wrapper around tikzpicture while preserving the tikzexternalize functionality (see this post, this and this one for reference where some of my ideas came from) a real ... 
[luatex] [environments] [lua]
 

asked by atticus https://tex.stackexchange.com/landing/r/digest?cta=user&id=206293 Score of 1

8.20.3.3 add scrolling arrows to presentation (to switch between slides)

https://tex.stackexchange.com/landing/r/digest?cta=question&id=637642

how can i add scroll arrows to slides latex. 
to switch slides in pdf. 
i'm using overleaf beamer . 
thank you for helping . 
that 
that it completely describes my problem it completely describes my ... 
[beamer] [pdf] [overleaf] [presentations] [bar]
 

asked by Lasri Iliass https://tex.stackexchange.com/landing/r/digest?cta=user&id=266710 Score of 1