title: Get an array of the values of a key from an array of hashes?
body: <p>For an array like this:</p>
  
  <pre><code> a = [{a:'a',b:'3'},{a:'b',b:'2'},{a:'c',b:'1'}]
  </code></pre>
  
  <p>I would like to return an array containing values for <code>:a</code> keys, so:</p>
  
  <pre><code> ['a', 'b', 'c']
  </code></pre>
  
  <p>That can be done using:</p>
  
  <pre><code> a.map{|x|x[:a]}
  </code></pre>
  
  <p>I wonder if there is a native method in Rails or Ruby to do it like this?</p>
  
  <pre><code> a.something :a
  </code></pre>