text: #!/usr/bin/env python
  
  # Toy program to generate inverted index of word to line.
  # Takes input text file on stdin and prints output index on stdout.
  
  import sys
  import os
  
  words = {}
  
  mainfile = sys.argv[1]
  indexfile = sys.argv[1] + ".idx1"
  
  main = open(mainfile)
  index = open(indexfile, "w")
  
  linenum = 0
  for l in main:
      linenum += 1
      l = l.rstrip().lower().replace(".", "").replace(",", "").replace(";", "").replace("-", " ")
      for w in l.split(" "):
          if w:
              if w not in words:
                  words[w] = set()
              words[w].add(linenum)
  
  for w in sorted(words.keys()):
      index.write("%s: %s" % (w, ", ".join((str(i) for i in words[w]))) + "\n")
  
  open(os.path.splitext(sys.argv[1])[0] + ".idx2", "w")
  open(sys.argv[1] + ".idx3", "w")
  open(sys.argv[1] + ".idx4", "w")
  open(sys.argv[1] + ".idx5", "w")
  