Can you give an example of refactoring code to follow SRP?

Before (SRP Violation):

public class Invoice
{
public void GenerateInvoice() { /* logic */ }
public void SaveToDatabase() { /* logic */ }
public void SendEmail() { /* logic */ }
}

This class has 3 responsibilities: generating, saving, and emailing.

fter (SRP-compliant):

public class InvoiceGenerator
{
public void Generate() { /* logic */ }
}
public class InvoiceRepository
{
public void Save(Invoice invoice) { /* logic */ }
}
public class EmailService
{
public void Send(Invoice invoice) { /* logic */ }
}

Now each class has a single reason to change.