title: Python, finding unique words in multiple lists
body: <p>I have the following code:</p>
  
  <pre><code> a= ['hello','how','are','hello','you']
   b= ['hello','how','you','today']
   len_b=len(b)
  
   for word in a:
  
        count=0
        while count &lt; len_b:
  
             if word == b[count]:       
                 a.remove(word)
                 break
  
             else:
                 count=count+1
  
   print a  
  </code></pre>
  
  <p>The goal is that it basically outputs (contents of list a)-(contents of list b)
  so the wanted result in this case would be a = ['are','hello'] </p>
  
  <p>but when i run my code i get a= ['how','are','you']</p>
  
  <p>can anybody either point out what is wrong with my implementation, or is there another better way to solve this?</p>