shutdown_demo.py code from AIY Projects Essential Guide

[lucyhattersley]

Billy Rutledge passed on a request for this shutdown_demo.py code. It is being used in the AIY Projects Essentials book and may come in handy.

#!/usr/bin/env python3

import aiy.audio
import aiy.cloudspeech
import aiy.voicehat
import subprocess

def main():
    recognizer = aiy.cloudspeech.get_recognizer()
    recognizer.expect_phrase('shutdown')
    
    button = aiy.voicehat.get_button()
    aiy.audio.get_recorder().start()
    
    while True:
        print('Press the button and speak')
        button.wait_for_press()
        print('Listening...')
        text = recognizer.recognize()
        if text is None:
            print('Sorry, I did not hear you.')
        else:
            print('You said "', text, '"')
            if 'shutdown' in text:
                subprocess.call(["sudo", "shutdown", "-h", "now"])

if __name__ == '__main__':
    main()

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[ensonic]

We have a similar action in
https://github.com/google/aiyprojects-raspbian/blob/master/src/action.py#L238
and trigger it with a phrase 'raspberry power off' to avoid accidental shutdowns. Maybe we can use the same phrase? WDYT?

[drigz]

@enetor has pushed this file into the voicekit branch (6af695b) so we can close this PR.