Cannot get this to work - get the error:

Challenge Not yet complete... here's what's wrong: 
The 'Accounts' class 'onBeforeUpdate' method does not appear to be calculating the Levenshtein distance between the phrase default Description ‘Domain classes rock!’ and the value in the updated Description and storing the result in the Annual Revenue field correctly.

Here's my code in the Accounts class:
 

public class Accounts extends fflib_SObjectDomain {

    public Accounts(List<Account> sObjectList) {
        super(sObjectList);
    }
    
    public class Constructor implements fflib_SObjectDomain.IConstructable {
        public fflib_SObjectDomain construct(List<sObject> sObjectList) {
            return new Accounts(sObjectList);
        }
    }
    
    public override void onBeforeInsert() {
        List<Account> newAccounts = new List<Account>();
        
        for (Account acct : (List<Account>) Records) {
            acct.Description = 'Domain classes rock!';
            newAccounts.add(acct);
        }
        
        fflib_SObjectUnitOfWork uow = new fflib_SObjectUnitOfWork(new Schema.SObjectType[] { Account.SObjectType });
        uow.registerNew(newAccounts);
    }
    
    public override void onBeforeUpdate(Map<Id,sObject> Records) {
        String rock = 'Domain classes rock!';
        Set<Id> Ids = Records.keySet();
        
        List<Account> accountList = [SELECT Id, Description, AnnualRevenue 
                                     FROM Account 
                                     WHERE Id IN :Ids];
        
        List<Account> updatedAccounts = new List<Account>();
        
        for (Account acct : accountList) {
            if (acct.Description != NULL) {
                acct.AnnualRevenue = rock.getLevenshteinDistance(acct.Description);
                updatedAccounts.add(acct);
            }
        }
        
        fflib_SObjectUnitOfWork uow = new fflib_SObjectUnitOfWork(new Schema.SObjectType[] { Account.SObjectType });
        uow.registerDirty(updatedAccounts);
    }
    
    public override void onApplyDefaults() {
        String rock = 'Domain classes rock!';
        List<Account> accountList = (List<Account>)Records;
        List<Account> updatedAccounts = new List<Account>();
        
        for (Account acct : accountList) {
            if (acct.Description != NULL) {
                acct.AnnualRevenue = rock.getLevenshteinDistance(acct.Description);
                updatedAccounts.add(acct);
            }
        }
        
        fflib_SObjectUnitOfWork uow = new fflib_SObjectUnitOfWork(new Schema.SObjectType[] { Account.SObjectType });
        uow.registerDirty(updatedAccounts);
        uow.commitWork();
    }
}