fixed integrator, differentiator not having init function

src/openqlab/analysis/servo_design.py

@@ -189,6 +189,9 @@ class Integrator(Filter):
         Frequency were the ~1/f slope starts, defaults to 0.001 * `corner_frequency`.
     """
 
+    def __init__(self, corner_frequency, second_parameter=None, enabled=True):
+        super().__init__(corner_frequency, second_parameter, enabled)
+
     def calculate(self):
         z = -self.corner_frequency
         if self.sF is None:
@@ -224,6 +227,9 @@ class Differentiator(Filter):
 
     """
 
+    def __init__(self, corner_frequency, second_parameter=None, enabled=True):
+        super().__init__(corner_frequency, second_parameter, enabled)
+
     def calculate(self):
         z = -self.corner_frequency
         if self.sF is None: