protected override bool ReceiveCommand(object message)
        {
            if (message is CreateCustomer)
            {
                var cmd = (CreateCustomer) message;
                
                Id = cmd.CustomerId;

                var evt = new CustomerCreated
                {
                    CustomerId = cmd.CustomerId,
                    CustomerName = cmd.CustomerName
                };

                Persist(evt, Create);

                Sender.Tell(evt.CustomerId, Self);

                return true;
            } 
            
            if (message is ChangeCustomerName)
            {
                var cmd = (ChangeCustomerName) message;
                var evt = new CustomerNameChanged
                {
                    CustomerId = Id,
                    NewCustomerName = cmd.NewName
                };

                Persist(evt, ChangeName);

                Sender.Tell(true, Self);

                return true;
            }
            
            if (message is string)
            {
                var cmd = (string) message;
                if (cmd == "snapshot")
                {
                    SaveSnapshot(_state);
                }

                return true;
            }

            return false;
        }
 private void ChangeName(CustomerNameChanged evt)
 {
     Name = evt.NewCustomerName;
 }