[ENHANCEMENT] Use modern abstract functionality

[oerc0122]

Is your feature request related to a problem? Please describe.
Currently, several abstract classes do not use @abstractmethod to highlight these abstractions and thus cannot verify whether child classes correctly implement them.

Describe the solution you'd like
Implementation of abstract methods.

Describe alternatives you've considered
N/A

Additional context

Example code

from abc import ABC, ABCMeta, abstractmethod

class Geoff(metaclass=ABCMeta):
    def __init__(self):
        self.x = 7

    def calculate(self):
        raise NotImplementedError()

class SubGeoff(Geoff):
    ...

q = SubGeoff()

print(q.x)


class GeoffAbs(metaclass=ABCMeta):
    def __init__(self):
        self.x = 7

    @abstractmethod
    def calculate(self):
        raise NotImplementedError()

class SubGeoffAbs(GeoffAbs):
    ...

w = SubGeoffAbs()
print(w.x)

$ python tmp.py
7
Traceback (most recent call last):
  File "/home/jacob/tmp.py", line 29, in <module>
    w = SubGeoffAbs()
TypeError: Can't instantiate abstract class SubGeoffAbs with abstract method calculate