title: How to undefine class in Ruby?
body: <p>Undefining a method in Ruby is pretty simple, I can just use <code>undef METHOD_NAME</code>.</p>
  
  <p>Is there anything similar for a class? I am on <code>MRI 1.9.2</code>. </p>
  
  <p>I have to undefine an ActiveRecord Model, run two lines of code, and restore the model back to its original form.</p>
  
  <p>The problem is, I have an model <code>Contact</code> and I am using a company's API and it happens that they have some class called <code>Contact</code>, and changing my model name would be lot of work for me. </p>
  
  <p>What can I do in this situation?</p>