* adding static type checking to basic_binary_tree.py
* Add static type checking to functions with None return type
* Applying code review comments
* Added missing import statement
* fix spaciing
* "cleaned up depth_of_tree"
* Add doctests and then streamline display() and is_full_binary_tree()
* added static typing to lazy_segment_tree.py
* added missing import statement
* modified variable names for left and right elements
* added static typing to lowest_common_ancestor.py
* fixed formatting
* modified files to meet style guidelines, edited docstrings and added some doctests
* added and fixed doctests in lazy_segment_tree.py
* fixed errors in doctests
Co-authored-by: Christian Clauss <cclauss@me.com>