How to use dictionary instead of if statement in python?

I have a function that pops-up a message box after you click on a button using PyQt4 in python. I use 'sender()' to determine which button was clicked and then set the text of pop-up window accordingly. This function works perfectly with 'if statements'. However I was wondering how do I write a function with same functionality using a dictionary (since there is no switch statement in python and there are too many if statements in my code)?

def pop_up(self):
    msg = QtGui.QMessageBox()
    msg.setIcon(QtGui.QMessageBox.Information)
    sender = self.MainWindow.sender()

    if sender is self.button1:
        msg.setText("show message 1")
    elif sender is self.button2:
        msg.setText("show message 2")
    elif sender is self.button3:
        msg.setText("show message 3")
    elif sender is self.button4:
        msg.setText("show message 4")
    elif sender is self.button5:
        msg.setText("show message 5")
    elif sender is self.button6:
        msg.setText("show message 6")
    .
    .
    .
    .
    .
    elif sender is self.button36:
        msg.setText("show message 36")


    msg.exec()