<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def clear(self):
 """Removes all panel from the CodeEditor."""

        for i in range(4):
            while len(self._panels[i]):
                key = sorted(list(self._panels[i].keys()))[0]
                panel = self.remove(key)
                panel.setParent(None)
                panel.deleteLater()