title: Getting error "expected character buffer object" and I don't know why
body: <pre><code>import string
  
  file = open('Text.txt')
  dataArray = file.read()
  file.close()
  
  dataArray = str(dataArray)
  letters = []
  
  qString = ""
  for j in dataArray:
      if j.islower() == True:
      qString = qString + "l"
  else:
      qString = qString + "u"
  
  for i in range(0,len(dataArray)):
      indexNum = qString.find("luuuluuul")
      letters.append(dataArray[indexNum+4])
      qString.replace(indexNum+4,"-")
  
  print letters
  </code></pre>
  
  <p>I'm programming in python, and attempting to find a sequence of letters in a text file that goes 1 lowercase letter, 3 uppercase letters, 1 lowercase letter, 3 uppercase letters, 1 lowercase letter. What I have should work as far as I know, but it gives an an error "expected character buffer object". I'm wondering if anyone can see where I'm going wrong. The error is ocuring from: 
      qString.replace(indexNum+4,"-")</p>