old_contents: def generate_ngrams(text, n):
      ''' Generates all possible n-grams of a
      piece of text
  
      >>> text = 'this is a random piece'
      >>> n = 2
      >>> generate_ngrams(text, n)
      this is
      is a
      a random
      random piece
      '''
      text_array = text.split(' ')
      for i in range(0, len(text_array) - n + 1):
          print text_array[i:i + n]
  
  generate_ngrams('this is a random piece', 2)
  generate_ngrams('this is a random piece', 3)
  
new_contents: def generate_ngrams(text, n):
      ''' Generates all possible n-grams of a
      piece of text
  
      >>> text = 'this is a random piece'
      >>> n = 2
      >>> generate_ngrams(text, n)
      this is
      is a
      a random
      random piece
      '''
      text_array = text.split(' ')
      ngram_list = []
      for i in range(0, len(text_array) - n + 1):
          ngram_list.append(text_array[i:i + n])
      return ngram_list
  
  print generate_ngrams('this is a random piece', 2)
  print generate_ngrams('this is a random piece', 3)
  print generate_ngrams('this is a random piece', 4)
  
subject: Return a list of lists