fix number_of_digits bug (#2301)

* fix bug

* test larger negative

* fixup! Format Python code with psf/black push

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

data_structures/binary_tree/basic_binary_tree.py

@@ -5,6 +5,7 @@ class Node:
     """
     A Node has data variable and pointers to Nodes to its left and right.
     """
+
     def __init__(self, data: int) -> None:
         self.data = data
         self.left: Optional[Node] = None