How can I switch current window with pywin32?

Question

I want to switch the current window with python. I saw a post that should answer my question in Python Window Activation, but it didn't. First I made a class to put the function in:

class WindorMgr:
    def change_window(self, name, in_window_name=False):
        from win32gui import EnumWindows, SetForegroundWindow, GetWindowText
        from re import match

        handle = None

        def find_window(num, name):
            if not in_window_name:
                if match(name, str(GetWindowText(num))) is not None:
                    SetForegroundWindow(num)
            else:
                name = name.lower()
                try:
                    handle = str(GetWindowText(num)).lower()
                    handle.index(name)
                    SetForegroundWindow(num)
                except:
                    pass
                       
        EnumWindows(find_window, name)

I don't know if it's okay to put a methond in another method, but it worked, so I made like that. When I run the script it actually works, but it only changes the window once.

I made the test like that:

if __name__ == '__main__':
    from time import sleep
    windowmgr = WindowMgr()
    windowmgr.change_window('opera', in_window_name=True)
    sleep(5)
    windowmgr.change_window('Word')
    

As I said, it changes the window once. When the script starts running, it changes the window to Opera browser, but after the 4 seconds it doesn't change to Microsoft Word. Instead the Microsoft Word icon turns yellow. What should I do to make it work as I want it to?