tweet_sentiment uses codecs library to import output.txt. Line-by-line
processing of the file allows isolation of each tweet there by
allowing json.loads() to create directory from the text input.

The directory can be interrogated by: tweet['lang'] to determine the language
of the tweet, tweet['source'] to determine the source, and finally
tweet['text'] to determine the contents of the tweet.
tweet text extraction with catching an exception is complete...
finished Problem 2: calculate sentiment of tweet
installed and accessed nltk....