#Library Management System
##Entities:
- Customer
- Librarian
- Book
- Location
##Prerequisites:
Each book is placed under one location.
Actions
###Librarian:
- A librarian can create / update / delete a customer, location or a book.
- A librarian can place a book in a location
- A librarian can see the books borrowed by customers
###Customer:
- A customer can borrow a book.
- A customer can return a book.