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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 needs(cls, *service_names):
 """A class decorator to indicate that an XBlock class needs particular services."""

        def _decorator(cls_):                                # pylint: disable=missing-docstring
            for service_name in service_names:
                cls_._services_requested[service_name] = "need"  # pylint: disable=protected-access
            return cls_
        return _decorator