input: Write a function to tokenize a given text and return the list of tokens. The function should use the NLTK library's word_tokenize method for tokenization. If the input text is empty, the function should return an empty list.
  
  assert tokenize_text('Python is an interpreted, high-level, general-purpose programming language.')==['Python', 'is', 'an', 'interpreted', ',', 'high-level', ',', 'general-purpose', 'programming', 'language', '.']
  assert tokenize_text('')==[]
  assert tokenize_text('Hello world!')==['Hello', 'world', '!']
output: def tokenize_text(text):
      if not text:
          return []
      return word_tokenize(text)