# Assumptions
– A borrower may borrow a book copy of a certain barcode on a specific day at most once.
– A borrower may return a book copy of a certain barcode on a specific day at most once.
– A borrower may reserve a book copy of a certain barcode on a specific day at monst once.
– Number of borrowers less than 1e10
– Number of branches less than 1e10
– Number of managers less than 1e10
– Branch name no more than 100 characters
– Phone number has 10 characters
– Number of editions less than 1000