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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 set_knowledge_category(self, grade_id):
 """Sets the knowledge category. arg: grade_id (osid.id.Id):
 the new knowledge category raise: InvalidArgument - ``grade_id`` is invalid raise: NoAccess - ``grade_id`` cannot be modified raise: NullArgument - ``grade_id`` is ``null`` *compliance: mandatory -- This method must be implemented.* """

        # Implemented from template for osid.resource.ResourceForm.set_avatar_template
        if self.get_knowledge_category_metadata().is_read_only():
            raise errors.NoAccess()
        if not self._is_valid_id(grade_id):
            raise errors.InvalidArgument()
        self._my_map['knowledgeCategoryId'] = str(grade_id)