title: Optimizing a problem in OpenMDAO so that objective takes specific value
body: <p>I want to know if it is possible to optimize a problem in OpenMDAO in such a way that the objective approaches a specified value rather than minimizing or maximizing the objective?</p>
  <p>For example:</p>
  <pre><code>prob.model.add_objective(&quot;objective1&quot;, equals=10)
  </code></pre>
  <p>as in specifying constraints is not possible.</p>