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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 watch(self, key, pipeline=False):
 """Watch the given key. Marks the given key to be watch for conditional execution of a transaction. Args: key (str):
 Key that needs to be watched pipeline (bool):
 True, start a transaction block. Default false. """

        if pipeline:
            self._pipeline.watch(key)
        else:
            self._db.watch(key)