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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _find_existing_instance(self):
 """ I find existing VMs that are already running that might be orphaned instances of this worker. """

        if not self.connection:
            return None

        domains = yield self.connection.all()
        for d in domains:
            name = yield d.name()
            if name.startswith(self.workername):
                self.domain = d
                break

        self.ready = True