如何从按钮调用外部源函数。[Python]

import tkinter as tk

def external_function():
    # 外部源函数的具体实现
    pass

def button_click():
    external_function()

root = tk.Tk()
button = tk.Button(root, text="调用外部源函数", command=button_click)
button.pack()

root.mainloop()

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QPushButton

def external_function():
    # 外部源函数的具体实现
    pass

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        button = QPushButton("调用外部源函数", self)
        button.clicked.connect(self.button_click)

    def button_click(self):
        external_function()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    mainWindow = MainWindow()
    mainWindow.show()
    sys.exit(app.exec_())