<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def update(self, *names: str) -> 'ListTree': """Add all the mailbox names to the tree, filling in any missing nodes. Args: names: The names of the mailboxes. """

        for name in names:
            parts = name.split(self._delimiter)
            self._root.add(*parts)
        return self