title: Counting the number of unique words in a list
body: <p>Using the following code from <a href="https://stackoverflow.com/a/11899925">https://stackoverflow.com/a/11899925</a>, I am able to find if a word is unique or not (by comparing if it was used once or greater than once):</p>
  
  <pre><code>helloString = ['hello', 'world', 'world']
  count = {}
  for word in helloString :
     if word in count :
        count[word] += 1
     else:
        count[word] = 1
  </code></pre>
  
  <p>But, if I were to have a string with hundreds of words, how would I be able to count the number of unique words within that string?</p>
  
  <p>For example, my code has:</p>
  
  <pre><code>uniqueWordCount = 0
  helloString = ['hello', 'world', 'world', 'how', 'are', 'you', 'doing', 'today']
  count = {}
  for word in words :
     if word in count :
        count[word] += 1
     else:
        count[word] = 1
  </code></pre>
  
  <p>How would I be able to set <code>uniqueWordCount</code> to <code>6</code>? Usually, I am really good at solving these types of algorithmic puzzles, but I have been unsuccessful with figuring this one out. I feel as if it is right beneath my nose.</p>