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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 plugins(self):
 """Lazily load iotile plugins only on demand. This is a slow operation on computers with a slow FS and is rarely accessed information, so only compute it when it is actually asked for. """


        if self._plugins is None:
            self._plugins = {}

            for _, plugin in self.load_extensions('iotile.plugin'):
                links = plugin()
                for name, value in links:
                    self._plugins[name] = value

        return self._plugins