Precision must be a nonnegative integer (#2013)

* Precision must be a nonnegative integer

* fixup! Format Python code with psf/black push

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>

data_structures/linked_list/singly_linked_list.py

@@ -106,7 +106,7 @@ class LinkedList:
                 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