I am not to far into Python to tell You about pendants to statics and finals, but maybe the Python phrasing could be more 'hunam talk' like:
"""The base class relies on You to define the missing methods customize1 and customize2 when called from the base class."""
If You want to make it absolutely clear to the programmer, then define them like
def customize1(self):
raise NotImplementedError
def customize2(self):
raise NotImplementedError
This way they have to be implemented by the descendant (at least I think so...)