How Web Forms are generated? Cannot find the source code on Github

I am looking at frappe source code on Github ( https://github.com/frappe/frappe ) and I am trying to find the source code where the Web Forms are generated.

Can you point me out where to find the source?

Regards.

What is the purpose ? Any specific functionality you are looking at ?

If it help this

inherits from this

I want to use the code and maybe modify it to generate Web Form based on requirement of the company that I am working.

Thanks a lot. I will take a look.