src/main/java/seedu/address/logic/commands/UndoableCommand.java
private void saveAddressBookSnapshot() {
        requireNonNull(model);
        this.previousAddressBook = new AddressBook(model.getAddressBook());
        this.previousActiveListIsAll = model.getActiveIsAllBool();
    }
/**
     * Stores the current state of {@code model#addressBook}.
     */
Stores the current state of  model#addressBook.
Stores the current state of model#addressBook .
private void saveAddressBookSnapshot() {
        requireNonNull(model);
        this.previousAddressBook = new AddressBook(model.getAddressBook());
        this.previousActiveListIsAll = model.getActiveIsAllBool();
    }
private void saveAddressBookSnapshot ( ) { requireNonNull ( model ) ; this . previousAddressBook = new AddressBook ( model . getAddressBook ( ) ) ; this . previousActiveListIsAll = model . getActiveIsAllBool ( ) ; }
Stores the current state of {@code model#addressBook}.
Stores the current state of { @code model#addressBook } .