diff --git a/pina/model/layers/__init__.py b/pina/model/layers/__init__.py
index 950632f..87ea4e1 100644
--- a/pina/model/layers/__init__.py
+++ b/pina/model/layers/__init__.py
@@ -11,7 +11,7 @@ __all__ = [
     "PODBlock",
     "PeriodicBoundaryEmbedding",
     "AVNOBlock",
-    "AdaptiveActivationFunction"
+    "AdaptiveActivationFunction",
 ]
 
 from .convolution_2d import ContinuousConvBlock
diff --git a/pina/model/layers/adaptive_func.py b/pina/model/layers/adaptive_func.py
index fc23970..3bfc4be 100644
--- a/pina/model/layers/adaptive_func.py
+++ b/pina/model/layers/adaptive_func.py
@@ -40,7 +40,7 @@ class AdaptiveActivationFunction(torch.nn.Module):
         Parameter containing:
         tensor(1., requires_grad=True)
         >>>
-    
+
     .. seealso::
 
         **Original reference**: Godfrey, Luke B., and Michael S. Gashler.
@@ -50,7 +50,7 @@ class AdaptiveActivationFunction(torch.nn.Module):
         knowledge engineering and knowledge management (IC3K).
         Vol. 1. IEEE, 2015. DOI: `arXiv preprint arXiv:1602.01321.
         <https://arxiv.org/abs/1602.01321>`_.
-    
+
     """
 
     def __init__(self, func, alpha=None, beta=None, gamma=None, fixed=None):
@@ -77,17 +77,18 @@ class AdaptiveActivationFunction(torch.nn.Module):
         # see if there are fixed variables
         if fixed is not None:
             check_consistency(fixed, str)
-            if not all(key in ['alpha', 'beta', 'gamma'] for key in fixed):
-                raise TypeError("Fixed keys must be in "
-                                "['alpha', 'beta', 'gamma'].")
+            if not all(key in ["alpha", "beta", "gamma"] for key in fixed):
+                raise TypeError(
+                    "Fixed keys must be in [`alpha`, `beta`, `gamma`]."
+                )
 
         # initialize alpha, beta, gamma if they are None
         if alpha is None:
-            alpha = 1.
+            alpha = 1.0
         if beta is None:
-            beta = 1.
+            beta = 1.0
         if gamma is None:
-            gamma = 0.
+            gamma = 0.0
 
         # checking consistency
         check_consistency(alpha, (float, complex))
@@ -104,20 +105,20 @@ class AdaptiveActivationFunction(torch.nn.Module):
         # setting not fixed variables as torch.nn.Parameter with gradient
         # registering the buffer for the one which are fixed, buffers by
         # default are saved alongside trainable parameters
-        if 'alpha' not in (fixed or []):
+        if "alpha" not in (fixed or []):
             self._alpha = torch.nn.Parameter(alpha, requires_grad=True)
         else:
-            self.register_buffer('alpha', alpha)
-            
-        if 'beta' not in (fixed or []):
+            self.register_buffer("alpha", alpha)
+
+        if "beta" not in (fixed or []):
             self._beta = torch.nn.Parameter(beta, requires_grad=True)
         else:
-            self.register_buffer('beta', beta)
-            
-        if 'gamma' not in (fixed or []):
+            self.register_buffer("beta", beta)
+
+        if "gamma" not in (fixed or []):
             self._gamma = torch.nn.Parameter(gamma, requires_grad=True)
         else:
-            self.register_buffer('gamma', gamma)
+            self.register_buffer("gamma", gamma)
 
         # registering function
         self._func = func
@@ -128,21 +129,21 @@ class AdaptiveActivationFunction(torch.nn.Module):
         Applies the function to the input elementwise.
         """
         return self.alpha * (self._func(self.beta * x + self.gamma))
-    
+
     @property
     def alpha(self):
         """
         The alpha variable
         """
         return self._alpha
-    
+
     @property
     def beta(self):
         """
         The alpha variable
         """
         return self._beta
-    
+
     @property
     def gamma(self):
         """