text: import string
  
  def is_pangram(sentence):
      letters = set(string.ascii_lowercase)
      return is_panagram_help(sentence.lower(), letters)
  
  def is_panagram_help(sentence, letters):
      print(letters)
      if len(letters) == 0:
          return True
      elif len(sentence) == 0:
          return False
      else:
          letters.discard(sentence[0])
          return is_panagram_help(sentence[1:], 
                      letters)
  
  