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# Grab application default credentials from the environment
credentials, _ = google.auth.default(scopes=[SPEECH_SCOPE])

# Create a secure channel using the credentials.

http_request = google.auth.transport.requests.Request()
target = '{}:{}'.format(host, port)

return google.auth.transport.grpc.secure_authorized_channel(

credentials, http_request, target)

def _audio_data_generator(buff):

"""A generator that yields all available data in the given buffer.
Args:

buff - a Queue object, where each element is a chunk of data.
Yields:

A chunk of data that is the aggregate of all chunks of data in `buff`.
The function will block until at least one data chunk is available.

"""
stop = False

while not stop:
# Use a blocking get() to ensure there's at least one chunk of data.

data = [buff.get()]

# Now consume whatever other data's still buffered.
while True:

try:
data.append(buff.get(block=False))

except queue.Empty:
break

# `None` in the buffer signals that the audio stream is closed. Yield

# the final bit of the buffer and exit the loop.
if None in data:

stop = True
data.remove(None)

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