def METHOD_NAME(self):
    filename, _ = QtWidgets.QFileDialog.getOpenFileName(
        filter="Touchstone Files (*.s1p *.s2p);;All files (*.*)"
    )
    if filename != "":
        self.app.data.s11 = []
        self.app.data.s21 = []
        t = Touchstone(filename)
        t.load()
        self.app.saveData(t.s11, t.s21, filename)
        self.app.dataUpdated()