Use hasattr() in has_attribute

[s-t-e-v-e-n-k]

has_attribute uses dunder methods that getattr() calls, and there is in fact a wrapper function that handles all of this for us, hasattr(). Switch to using it.

[oddstr13]

This looks like an useless function, I propose deprecating it for now, and removing it completely at some point later.

[s-t-e-v-e-n-k]

It was added explicitly in README, maybe we can just drop it?