input: Write a function to create a Text-to-Speech Python application to read out a simple sentence. If the sentence is provided, it should be spoken aloud using the pyttsx3 library.
  def text_to_speech(sentence):
      if not sentence:
          return "No sentence provided."
      engine = pyttsx3.init()
      engine.say(sentence)
      engine.runAndWait()
  
  assert text_to_speech("Hello, this is a simple sentence")==None
  assert text_to_speech("")=="No sentence provided."
output: def text_to_speech(sentence):
      if not sentence:
          return "No sentence provided."
      engine = pyttsx3.init()
      engine.say(sentence)
      engine.runAndWait()