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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 install_monitor(self, monitor):
 """Install monitor on all executors."""

        if self.sym_gen is not None:
            raise NotImplementedError("Monitoring is not implemented for bucketing")

        for train_exec in self.execgrp.train_execs:
            monitor.install(train_exec)