pyttsx3 not taking voice code example

Example 1: how to change the rate of speech in pyttsx3

import pyttsx3

engine = pyttsx3.init()
engine.setProperty("rate", 178)
engine.say("I am the text spoken after changing the speech rate.")
engine.runAndWait()

Example 2: pyttsx3 NameError: name 'voices' is not defined

engine = pyttsx3.init() # Object Creation

voice = engine.setProperty('voice', voices[0].id)

engine.say("I will speak this text")
engine.runAndWait()