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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 defaults(cls, *options, **kwargs):
 """Set default options for a session. Set default options for a session. whether in a Python script or a Jupyter notebook. Args: *options: Option objects used to specify the defaults. backend: The plotting extension the options apply to """

        if kwargs and len(kwargs) != 1 and list(kwargs.keys())[0] != 'backend':
            raise Exception('opts.defaults only accepts "backend" keyword argument')

        cls._linemagic(cls._expand_options(merge_options_to_dict(options)), backend=kwargs.get('backend'))