old_contents: 
  txt = "the quick brown fox jumped over thethe lazy dog"
  
  txt2 = txt.replace("the","a")
  
  print txt
  print txt2
  
new_contents: 
  txt = "the quick brown fox jumped over thethe lazy dog"
  
  txt2 = txt.replace("the","a")
  
  print txt
  print txt2
  
  print txt.replace("the", "a", 0)
  print txt.replace("the", "a", 1)
  print txt.replace("the", "a", 2)
  print txt.replace("the", "a", 3)
  print txt.replace("the", "a", 4)
  print txt.replace("the", "a", 50)
  
subject: Expand the str.replace() tests