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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 _get(cls, kwarg_name):

 """ Returns a Param Class Instance, by its kwarg or param name """

        param_classes = cls._discover_params()
        try:
            param_class = param_classes[kwarg_name]
        except KeyError:
            raise ValueError('invalid param keyword {}'.format(kwarg_name))
        else:
            return param_class