title: nltk function to count occurrences of certain words
body: <p>In the nltk book there is the question
  "Read in the texts of the State of the Union addresses, using the state_union corpus reader. Count occurrences of men, women, and people in each document. What has happened to the usage of these words over time?"</p>
  
  <p>I thought I could use a function like state_union('1945-Truman.txt').count('men') 
  However, there are over 60 texts in this State Union corpa and I feel like there has to be an easier way to see the count of these words for each one instead of repeating this function over and over for each text.</p>