How can a generator receive external values through send()? Write an example of a generator that accepts the word 'stop' and stops.

A generator in Python can receive values from outside using the send() method. When calling send(value), the generator resumes execution and the yield expression returns the passed value value. This allows dynamic influence on the generator's behavior.

Example of a generator that accepts the word 'stop' and stops:

def stop_generator():
    while True:
        word = yield
        if word == 'stop':
            print('Stopping generator')
            break
        else:
            print(f'Received word: {word}')

# Usage
g = stop_generator()
next(g)  # Start generator up to the first yield

g.send('hello')  # Will print: Received word: hello

g.send('world')  # Will print: Received word: world

g.send('stop')   # Will print: Stopping generator

Note that before the first send(), you need to start the generator up to the first yield with next().