Implement IIRFilter class with detailed documentation and methods for coefficient setting and sample processing

Author: Aliyu kamal

audio_filters/iir_filter.py

@@ -52,9 +52,9 @@ def set_coefficients(self, a_coeffs: list[float], b_coeffs: list[float]) -> None
             ValueError: If the length of `a_coeffs` or `b_coeffs` does not match the order of the filter.
         """
         if len(a_coeffs) != self.order + 1:
-            raise ValueError(f"Expected {self.order + 1} coefficients for `a_coeffs`, got {len(a_coeffs)}")
+            raise ValueError("Expected {} coefficients for `a_coeffs`, got {}".format(self.order + 1, len(a_coeffs)))
         if len(b_coeffs) != self.order + 1:
-            raise ValueError(f"Expected {self.order + 1} coefficients for `b_coeffs`, got {len(b_coeffs)}")
+            raise ValueError("Expected {} coefficients for `b_coeffs`, got {}".format(self.order + 1, len(b_coeffs)))
 
         self.a_coeffs = a_coeffs
         self.b_coeffs = b_coeffs