title: How can I get source code of a method dynamically and also which file is this method locate in
body: <p>I would like to know whether I can get source code a method on the fly, and whether I can get which file is this method in.</p>
  
  <p>like </p>
  
  <pre><code>A.new.method(:a).SOURCE_CODE
  A.new.method(:a).FILE
  </code></pre>