Added tests and docstrings to fibonacci_heap.py

Author: mcawezome

data_structures/heap/fibonacci_heap.py

@@ -12,7 +12,6 @@
 - Merge: O(1)
 """
 
-
 class Node:
     """
     A node in a Fibonacci heap.
@@ -29,7 +28,6 @@ class Node:
         degree: Number of children.
         mark: Boolean indicating if node has lost a child.
     """
-
     def __init__(self, val):
         self.val = val
         self.parent = None
@@ -233,7 +231,7 @@ def __consolidate(self):
 
         This is an internal method that maintains the heap's structure.
         """
-        max_degree = int(self.size**0.5) + 1
+        max_degree = int(self.size ** 0.5) + 1
         degree_table = [None] * max_degree
 
         # Collect all roots
@@ -273,11 +271,11 @@ def __consolidate(self):
     def decrease_key(self, node, new_val):
         """
         Decreases the value of a node.
-
+        
         Args:
             node: The node whose value should be decreased.
             new_val: The new value for the node.
-
+        
         Raises:
             ValueError: If new value is greater than current value.
         """
@@ -301,9 +299,9 @@ def __cut(self, node, parent):
         Args:
             node: Node to be cut.
             parent: Parent of the node to be cut.
-        """ """
+        """"""
         Performs cascading cut operation.
-
+        
         Args:
             node: Starting node for cascading cut.
         """
@@ -326,7 +324,8 @@ def __cascading_cut(self, node):
             node: Starting node for cascading cut.
         """
 
-        if parent := node.parent:
+        parent = node.parent
+        if parent:
             if not node.mark:
                 node.mark = True
             else:
@@ -360,5 +359,4 @@ def print_tree(node, level=0):
 
 if __name__ == "__main__":
     import doctest
-
     doctest.testmod()