title: Unique word frequency using NLTK
body: <p>Code to get the unique Word Frequency for the following using NLTK.</p>
  
  <p><code>Seq Sentence</code> <br/>
  <code>1   Let's try to be Good.</code><br/>
  <code>2   Being good doesn't make sense.</code><br/>
  <code>3   Good is always good.</code></p>
  
  <p>Output:<br/>
  <code>{'good':3, 'let':1, 'try':1, 'to':1, 'be':1, 'being':1, 'doesn':1, 't':1, 'make':1, 'sense':1, 'is':1, 'always':1, '.':3, ''':2, 's':1}</code></p>