input: Write a function to create a Text-to-Speech Python application that reads out a simple sentence. The function should take a string input containing the sentence and use the pyttsx3 library to convert it to speech. Ensure the function initializes the pyttsx3 engine, says the sentence, and waits for the speech to complete.
  
  def text_to_speech(sentence):
      engine = pyttsx3.init()
      engine.say(sentence)
      engine.runAndWait()
  
  assert text_to_speech("Hello, this is a simple sentence")  # Expect the sentence to be read out loud
  assert text_to_speech("The quick brown fox jumps over the lazy dog.")  # Expect the sentence to be read out loud
  assert text_to_speech("Python is a popular programming language.")  # Expect the sentence to be read out loud
  assert text_to_speech("")  # Expect no speech output
  assert text_to_speech("12345")  # Expect the digits to be read out loud
output: def text_to_speech(sentence):
      engine = pyttsx3.init()
      engine.say(sentence)
      engine.runAndWait()