Return either 'tutor' or 'student' based on which radio
        button is selected.

def update_user_type(self):
        """Return either 'tutor' or 'student' based on which radio
        button is selected.
        """
        if self.rb_tutor.isChecked():
            self.user_type = 'tutor'
        elif self.rb_student.isChecked():
            self.user_type = 'student'
        self.accept()