input: Write a function to tokenize a given text using the NLTK library. The function should return a list of tokens.
  
  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("Natural Language Processing is fascinating!")==['Natural', 'Language', 'Processing', 'is', 'fascinating', '!']
  assert tokenize_text("")==[]
  assert tokenize_text("123 456 789")==['123', '456', '789']
  assert tokenize_text("Hello, World!")==['Hello', ',', 'World', '!']
output: def tokenize_text(text):
      from nltk.tokenize import word_tokenize
      return word_tokenize(text)