title: KeyError: 'pop from an empty set' python
body: <p>How do you get around this error while using <code>.pop</code>? I get that when it tries to return a number but there isn't one an error is raised but how do you get around it so the program keeps running?</p>
  
  <pre><code>def remove_element(self,integer):
      self.integer = integer
      self.members.pop()
  </code></pre>