singly_linked_list.py: psf/black

DIRECTORY.md

@@ -295,6 +295,7 @@
   * [Add](https://github.com/TheAlgorithms/Python/blob/master/maths/add.py)
   * [Aliquot Sum](https://github.com/TheAlgorithms/Python/blob/master/maths/aliquot_sum.py)
   * [Allocation Number](https://github.com/TheAlgorithms/Python/blob/master/maths/allocation_number.py)
+  * [Area](https://github.com/TheAlgorithms/Python/blob/master/maths/area.py)
   * [Area Under Curve](https://github.com/TheAlgorithms/Python/blob/master/maths/area_under_curve.py)
   * [Armstrong Numbers](https://github.com/TheAlgorithms/Python/blob/master/maths/armstrong_numbers.py)
   * [Average Mean](https://github.com/TheAlgorithms/Python/blob/master/maths/average_mean.py)

data_structures/linked_list/singly_linked_list.py

@@ -1,9 +1,9 @@
-class Node:  # create a Node
+class Node:
     def __init__(self, data):
-        self.data = data  # given data
-        self.next = None  # given next to None
+        self.data = data
+        self.next = None
 
-    def __repr__(self):  # string representation of a Node
+    def __repr__(self):
         return f"Node({self.data})"
 
 
@@ -106,7 +106,7 @@ def __setitem__(self, index, data):
                 raise IndexError("Index out of range.")
             current = current.next
         current.data = data
-       
+
     def __len__(self):
         """
         Return length of linked list i.e. number of nodes