title: python : TypeError: argument of type 'builtin_function_or_method' is not iterable
body: <p>So I've been trying to complete a spell_checker that takes a .txt and compare with the dictionary.txt to find incorrect words. the result should be print back the words from the .txt that are wrong.</p>
  
  <p>But I keep getting this error when trying to do my for loop:</p>
  
  <p>TypeError: argument of type 'builtin_function_or_method' is not iterable</p>
  
  <p>Here are my codes:</p>
  
  <pre><code>def spell_check(wordlist):
      opening = open('words.txt').read(). lower(). strip(' ')
      text = []
      conv = set(opening)
      conv1 = set(wordlist)
      conv2 = conv1.add
      return [x for x in conv if x not in conv2]
  </code></pre>
  
  <p>EDIT:
  I needed conv2, because i need to keep the errors in the same orders they are present; I don't want it to be ordered like a set. so if anyone has other insights on how to solve this problem as well. that would be great.</p>
  
  <p>If anyone can shine some light on this, that would be much appreciated!</p>