Update accelerator_util.py
I think this PR is far away from being ready to be merged.

It is not clear of the merits of the changes, and the description is inconsistent with the actual changes;
for example all of the docstrings have been removed while the description claimed improvements in the docstring. 
 Please don't use "add file"/"update file"/"fix file"/etc. commit messages. These are hard to reason about when looking at the history of the file/repository. Instead, please write explanatory git commit messages.

The commit message is also the title of the PR if the PR has only one commit. It is thus twice important to have commit messages that are relevant, as PRs would be easier to understand and easier to analyze in search results.

For how to write good quality git commit messages, please consult https://cbea.ms/git-commit/ 

We will automaticall close PRs by you if you don't take these suggestions into account
1. Introduced an AcceleratorType class to define accelerator types for better clarity. 
2. Created an AcceleratorSystem class to encapsulate the accelerator system's functionality.
3.  Removed global variables and used instance variables within the AcceleratorSystem class. 
4. Simplified the code structure and made it more organized. 
5. Removed unnecessary repetitive checks and error handling. 
6. Improved docstrings and comments for better understanding. 
7. Reorganized the code for improved readability.