Waiting for QThread without interupting main thread

[ecce]

How do you wait for a qthread to finish without blocking the main loop (thereby blocking the responsiveness of the main window)? I'm using PyQt5.

# When scan button is pressed
    def scan(self, e):
        for dev in self.deviceList:
            thread = TestThread(self, dev)
            thread.debugOutput.connect(self.updateTextEdit)
            thread.start()
            print("Thread finished")

# When scan button is pressed
    def scan(self, e):
        for dev in self.deviceList:
            thread = TestThread(self, dev)
            thread.debugOutput.connect(self.updateTextEdit)
            thread.start()
            print("Thread finished")

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The thread(s) started in this piece of code do GUI updates to inform the user of what's going on. I do not want to block that. I want the "thread finished" to be printed out once the thread actually is finished.