title: name 'nltk' is not defined
body: <p><a href="https://i.stack.imgur.com/LC2NV.png" rel="nofollow noreferrer">The nltk module is running with other libraries in the corpus folder.</a></p>
  
  <p><a href="https://i.stack.imgur.com/q2d25.png" rel="nofollow noreferrer">My Code</a></p>
  
  <p>I've already tried putting 'import nltk' at first but it is still the same, and also I've tried 'from nltk.tokenize import 'PunktSentenceTokenizer'. I don't know why the Python shell can't find the definition of the nltk. How should I address this? I am still learning how to write and code python.</p>