* Simplify sudoku.is_completed() using builtin all()
Simplify __sudoku.is_completed()__ using Python builtin function [__all()__](https://docs.python.org/3/library/functions.html#all).
* fixup! Format Python code with psf/black push
* Update sudoku.py
* fixup! Format Python code with psf/black push
* Old style exception -> new style for Python 3
* updating DIRECTORY.md
* Update convex_hull.py
* fixup! Format Python code with psf/black push
* e.args[0] = "msg"
* ValueError: could not convert string to float: 'pi'
* Update convex_hull.py
* fixup! Format Python code with psf/black push
* Fix out of range error in bellman_ford.py
* Update bellman_ford.py
* fixup! Format Python code with psf/black push
* Enhance the print function
* fixup! Format Python code with psf/black push
* Added print function into matrix_multiplication_addition.py and removed blank space in data_structures/binary tree directory
* Removed .vs/ folder per #893
* Rename matrix_multiplication_addition.py to matrix_operation.py
* Fixing lgtm issue in basic_graphs per ##1024
* Fixed lgtm issue per @cclauss recommendation in #1024
* Added doctest and more explanation about Dijkstra execution.
* tests were not passing with python2 due to missing __init__.py file at number_theory folder
* Removed the dot at the beginning of the imported modules names because 'python3 -m doctest -v data_structures/hashing/*.py' and 'python3 -m doctest -v data_structures/stacks/*.py' were failing not finding hash_table.py and stack.py modules.
* Moved global code to main scope and added doctest for project euler problems 1 to 14.
* Added test case for negative input.
* Changed N variable to do not use end of line scape because in case there is a space after it the script will break making it much more error prone.
* Added problems description and doctests to the ones that were missing. Limited line length to 79 and executed python black over all scripts.
* Changed the way files are loaded to support pytest call.
* Added __init__.py to problems to make them modules and allow pytest execution.
* Added project_euler folder to test units execution
* Changed 'os.path.split(os.path.realpath(__file__))' to 'os.path.dirname()'
I've added comments to make understanding this method a little easier for those that are not familiar. This should close out #727 .
Other changes:
1. added if __name__ == '__main__' rather than the "# MAIN" comment
2. put in return for distances and vertices. Previously everything was just printed out, but someone may find it useful to have the algorithm return something.
3. Other PEP8 changes
4. Added example input and expected output as a check to make sure any future changes will give the same output.
* organized graph algorithms
* all graph algorithms in Graphs/ folder
* all graph algorithms are in one folder
* Rename number theory/factorial_python.py to maths/factorial_python.py
