     self.emailTextFieldBecomeFirstResponder = Signal.merge(
       emailIsEmpty
         .takeWhen(self.nameTextFieldReturnProperty.signal)
-        .filter { $0 }
+        .filter(isTrue)
         .ignoreValues(),
 
       combineLatest(emailIsEmpty, nameIsEmpty)


      nameIsEmpty
        .takeWhen(self.passwordTextFieldReturnProperty.signal)
        .filter { $0 }
        .ignoreValues(),

      combineLatest(nameIsEmpty, passwordIsEmpty)

    self.passwordTextFieldBecomeFirstResponder = Signal.merge(
      passwordIsEmpty
        .takeWhen(self.emailTextFieldReturnProperty.signal)
        .filter(isTrue)
        .ignoreValues(),

      combineLatest(passwordIsEmpty, emailIsEmpty)
