title: add a patch to an agentset and remove a patch from an agents
body: <p>I have questions regarding netlogo agentset operation looking for help, thx.</p>
  
  <ol>
  <li><p>I want to add a patch, say patch-here, to a global agentset variable: mypatches. What is the correct way to write in a turtle procedure? I tried the following but it doesn't work:</p>
  
  <pre><code>set mypatches (patch-set mypatches patch-here)
  </code></pre></li>
  <li><p>I want to remove a patch, say patch-here, from a global agentset variable: mypatches. What is the correct way to write in a turtle procedure? The following code doesn't work because one-of operator assumes to remove self (which is a turtle) from mypatches but what I want is to remove patch-here from mypatches.</p>
  
  <pre><code>set mypatches one-of mypatches
  </code></pre></li>
  </ol>