input: Write a python function to recognize speech from an audio source using the SpeechRecognition library.
  assert recognize_speech() == "Hello World"  # Assuming "Hello World" is spoken
  assert recognize_speech() == "Testing one two three"  # Assuming "Testing one two three" is spoken
  assert recognize_speech() == "Python is great"  # Assuming "Python is great" is spoken
output: def recognize_speech():
      import speech_recognition as sr
      
      recognizer = sr.Recognizer()
      with sr.Microphone() as source:
          print("Please speak:")
          audio = recognizer.listen(source)
          
      try:
          text = recognizer.recognize_google(audio)
          return text
      except sr.UnknownValueError:
          return "Could not understand audio"
      except sr.RequestError:
          return "Could not request results; check your network connection"