title: How to delete entries from a dictionary using the value
body: <p>I have a dictionary collection as bleow:</p>
  
  <pre><code>mydic.addvalue(key1, val1)
  mydic.addvalue(key2, val1)
  mydic.addvalue(key3, val1)
  mydic.addvalue(key4, val2)
  mydic.addvalue(key5, val2)
  </code></pre>
  
  <p>From the above dictionary I want to delete all the entries where value == "val1", so that the result would have only following entry:</p>
  
  <pre><code>mydic.addvalue(key4, val2)
  mydic.addvalue(key5, val2)
  </code></pre>
  
  <p>My VB source code is on VS2008 and targeted for 3.5</p>