Markov chain Python script

#!/usr/bin/python
#	shaney.py              by Greg McFarlane
#	                       some editing by Joe Strout
#
#	search for "Mark V.  Shaney" on the WWW for more info!

import sys
import random
import string

def run(filenames=[]):
	text = ''
	if filenames==[]:
		#file = open( raw_input('Enter name of a textfile to read: '), 'r')
		text = sys.stdin.read() #" ".join(sys.argv[1:])
	else:
		for filename in filenames:
			file = open( filename, 'r')
			text += file.read()
			file.close()

	words = string.split(text)
	
	end_sentence = []
	dict = {}
	prev1 = ''
	prev2 = ''
	for word in words:
	  if prev1 != '' and prev2 != '':
	    key = (prev2, prev1)
	    if dict.has_key(key):
	      dict[key].append(word)
	    else:
	      dict[key] = [word]
	      if prev1[-1:] == '.':
	        end_sentence.append(key)
	  prev2 = prev1
	  prev1 = word
	
	if end_sentence == []:
	  print 'Sorry, there are no sentences in the text.'
	  return
	
	key = ()
	count = 10
	
	while 1:
	  if dict.has_key(key):
	    word = random.choice(dict[key])
	    print word,
	    key = (key[1], word)
	    if key in end_sentence:
	      print
	      count = count - 1
	      if count <= 0:
		break
	  else:
	    key = random.choice(end_sentence)
	
# end of run() function

# immediate-mode commands, for drag-and-drop or execfile() execution
if __name__ == '__main__':
	if len(sys.argv) >= 2:
		run(sys.argv[1:])		# accept a command-line filename
	else:
		run()
	print
	#raw_input("press Return>")
	quit()
else:
	print "Module shaney imported."
	print "To run, type: shaney.run()"
	print "To reload after changes to the source, type: reload(shaney)"

# end of shaney.py