Fix review issue

Author: MaximSmolskiy

audio_filters/show_response.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from abc import abstractmethod
 from math import pi
 from typing import Protocol
 
@@ -8,14 +9,14 @@
 
 
 class FilterType(Protocol):
-    def process(self, sample: float) -> float:  # noqa: ARG002
+    @abstractmethod
+    def process(self, sample: float) -> float:
         """
         Calculate y[n]
 
         >>> issubclass(FilterType, Protocol)
         True
         """
-        return 0.0
 
 
 def get_bounds(