input: Write a function to translate a text from English to French using the 'googletrans' library. The function should return the translated text. If the text is empty, the function should return an empty string.
  assert translate_text_to_french("Hello, this is a sample text to translate.") == "Bonjour, ceci est un texte d'échantillon à traduire."
  assert translate_text_to_french("") == ""
  assert translate_text_to_french("How are you?") == "Comment es-tu?"
  assert translate_text_to_french("My name is John.") == "Je m'appelle John."
  assert translate_text_to_french("Python is a popular programming language.") == "Python est un langage de programmation populaire."
output: def translate_text_to_french(text):
      if not text:
          return ""
      from googletrans import Translator
      translator = Translator()
      translation = translator.translate(text, src='en', dest='fr')
      return translation.text