text: from collections import defaultdict
  
  my_list=['a','b','c','d']
  for idx, val in enumerate( my_list ):
      print( idx, val)
  
  for idx, val in enumerate( my_list, 1):
      print( idx, val)
  
  word_summary = defaultdict(list)
  with open(__file__) as f:
      lines = f.readlines()
  
      for idx , line in enumerate( lines ):
          words = [w.strip().lower() for w in line.split()]
          for word in words:
              word_summary[word].append( idx )
  
  print( word_summary )
  
  data = [ (1, 2), (3, 4), (5, 6), (7, 8) ]
  #Correct!
  for n, (x,y) in enumerate(data):
      print( n , x + y )