I'm new to Python and I really need help on this, I've been looking everywhere but i can't find an answer.

I created a script that compares data from 2 Excels files and write a report in a new file. It's a long script that includes a lot of functions and objects.

Now I want to make this script usefull to anyone in my workteam and create a GUI. I am using Tkinter. I have created 2 buttons to ask the user for the files directory and store it in a list. 
I'd like my original script to use the two inputs and run when a third button is clicked on.

How should I include my script in the tkinder app script?? Here is my app:

```
from Tkinter import *
import Tkinter, Tkconstants, tkFileDialog

listfile = []

class simpleapp_tk(Tkinter.Tk):
    def __init__(self,parent):
        Tkinter.Tk.__init__(self,parent)
        self.parent = parent
        self.initialize()

    def initialize(self):

        button = Tkinter.Button(self,text=u"data 1",command=self.OnButtonClick)
        button2 = Tkinter.Button(self,text=u"data 2",command=self.OnButtonClick)
        #here is the third button to run the script, the command isn't right
        button3 = Tkinter.Button(self,text=u"Run script",command=self.OnButtonClick)
        button.pack(side='bottom',padx=15,pady=15) 
        button2.pack(side='bottom',padx=15,pady=15)
        button3.pack(side='bottom',padx=15,pady=15) 

    def OnButtonClick(self):
        x = tkFileDialog.askopenfilename(title='Please select data directory')
        listfile.append(x)

    # def OnButtonClick2(self):
        # Can I run my original script here?
        # I read one should not include a function into a function

if __name__ == "__main__":
    app = simpleapp_tk(None)
    app.title('my application')
    app.mainloop()

```