class InvoiceService:
    def create_invoice(self) -> str:
        return "invoice created by service"


class EmailService:
    def send(self, receiver, invoice) -> None:
        print(f'e-mail service is sending "{invoice}" to "{receiver}"')


class BusinessLogic:
    def __init__(self, invoice: InvoiceService, email: EmailService) -> None:
        self.email_service = email
        self.invoice_service = invoice

    def send(self, email_address) -> None:
        print('create invoice')
        invoice = self.invoice_service.create_invoice()
        print(f'sending invoice "{invoice}" to "{email_address}"')
        self.email_service.send(email_address, invoice)
        print('wat fott is is fott')