title: Count characters in a string from a list of characters
body: <p>I'm trying to write a function <code>count(s, chars)</code> that takes a string <code>s</code> and a
  list of characters <code>chars</code>. The function should count the number of
  occurrences of the letters given in <code>chars</code>.
  It should return a dictionary where the keys are
  the characters given in the list of characters <code>chars</code>.</p>
  
  <p>So for example:</p>
  
  <pre><code>In [1]: s = "Another test string with x and y but no capital h."
  In [2]: count(s, ['A', 'a', 'z'])
  Out[2]: 'A': 1, 'a': 3, 'z': 0
  </code></pre>
  
  <p>I made some code that can count all the characters of the string and return a dictionary of it:</p>
  
  <pre><code>return {i: s.count(i) for i in set(s)}
  </code></pre>
  
  <p>but I'm not sure how you would use a list of specific characters and return a dictionary...</p>