Proof of concept - fixed number of lines input with tkinter

import tkinter as tk

class textCollectingWindow():
    def __init__(self,linesOfText,prompt,btnText):
        self.theText = None

        self.root = tk.Tk()

        promptElement = tk.Label(self.root, text=prompt)
        promptElement.pack()

        self.entryBox = tk.Text(self.root, height=linesOfText)
        self.entryBox.pack()

        button = tk.Button(self.root, text = btnText,command=self.storeText)
        button.pack()

        while True:
            try:
                self.root.update()
            except:
                break

    def storeText(self):
        self.theText = self.entryBox.get("1.0", tk.END)
        self.theText = self.theText[:len(self.theText)-1]
        self.root.destroy()

    def getText(self):
        return self.theText


codeGetter = textCollectingWindow(2,'Enter two lines of code:','Add code')

userCode = codeGetter.getText()

with open('user\'s code.py','w') as userCodeFile:
    userCodeFile.write(userCode)

print('code added.')