* Another method added for GCD
* Now doctest fulfilled for added method.
* Update greatest_common_divisor.py
* Now unnecessary white spaces removed.
* Cycle_Detection_Undirected_Graph
Cycle_Detection_Undirected_Graph using Disjoint set DataStructure
* Update greatest_common_divisor.py again
* Again Updated cycle_detection_undirected_graph.py
* Delete cycle_detection_undirected_graph.py
* Add doctests and format the code with psf/black
* fixup: Typo
* Update greatest_common_divisor.py
* greatest_common_divisor()