title: [AttributeError: 'tuple' object has no attribute 'lower']
body: <pre><code>train = [('I love this sandwich.','pos'),
       ('This is an amazing place!', 'pos'),
       ('I feel very good about these beers.', 'pos'),
       ('This is my best work.', 'pos'),
       ('What an awesome view', 'pos'),
       ('I do not like this restaurant', 'neg'),
       ('I am tired of this stuff.', 'neg'),
       ("I can't deal with this.", 'neg'),
       ('He is my sworn enemy!.', 'neg'),
       ('My boss is horrible.', 'neg')
      ]
  </code></pre>
  
  <p>This is my training data and I'm using CountVectorizer but it is showing me error </p>
  
  <pre><code>from sklearn.feature_extraction.text import CountVectorizer
  cv = CountVectorizer()
  text_train_cv = cv.fit_transform(train)
  text_train_cv.shape
  </code></pre>
  
  <p>Kindly please help me out.</p>