in tts/src/tts/synthesizer.py [0:0]
def __call__(self, **kwargs):
rospy.loginfo('will call service {}'.format(self.service_name))
from tts.srv import Polly
rospy.wait_for_service(self.service_name)
polly = rospy.ServiceProxy(self.service_name, Polly)
return polly(polly_action='SynthesizeSpeech', **kwargs)