如何在Python 3中将一个函数的一个值的值用于另一个函数

Question

from PyQt4 import QtGui, QtCore
from selenium import webdriver

class Window(QtGui.QWidget):

    def __init__(self):
        QtGui.QWidget.__init__(self)
        self.button = QtGui.QPushButton('Test', self)
        self.button.clicked.connect(self.handleButton)
        layout = QtGui.QVBoxLayout(self)
        layout.addWidget(self.button)
        self.lbl = QtGui.QLabel(self)
        menu1=QtGui.QComboBox(self)
        for c in [" ","snak","python"]:
            menu1.addItem(c)

        menu1.activated[str].connect(self.b)
    def b(self,a):
        print (a) #it gives me the value selected in the menu option but the problem is i want to use the same value of "a" in another function

    def handleButton(self):
        driver = webdriver.Firefox()
        driver.get('http://google.com')
        driver.find_element_by_id("lst-ib").send_keys("a") # value of a should be same as value printed in function b

if __name__ == '__main__':

    import sys
    app = QtGui.QApplication(sys.argv)
    window = Window()
    window.show()
    sys.exit(app.exec_())