Sink log entries to bigquery.

def sink_bigquery(client, to_delete):
    """Sink log entries to bigquery."""
    dataset = _sink_bigquery_setup(client)
    to_delete.append(dataset)
    SINK_NAME = "robots-bigquery-%d" % (_millis(),)
    FILTER = "textPayload:robot"

    # [START sink_bigquery_create]
    DESTINATION = "bigquery.googleapis.com%s" % (dataset.path,)
    sink = client.sink(SINK_NAME, filter_=FILTER, destination=DESTINATION)
    assert not sink.exists()  # API call
    sink.create()  # API call
    assert sink.exists()  # API call
    # [END sink_bigquery_create]
    to_delete.insert(0, sink)