The standard library seems to contain various approaches to arithmetic operations on `nat`

.

This includes files mentioned to be “mostly OBSOLETE now”.

Depending on which files/modules are imported, the available properties/lemmas seem to be different.

What is the current recommended way to use arithmetic operations on `nat`

? what should be imported? is there a natural place where one can find (a list of) the available properties? if not, would it be interesting to create such an interface file?

Thanks.