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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 ajax_kindcat_arr(self, kind_sig):
        '''
        Get the sub category.

        根据kind值（kind_sig）获取相应分类，返回Json格式
        '''
        out_arr = {}
        for catinfo in MCategory.query_kind_cat(kind_sig):
            out_arr[catinfo.uid] = catinfo.name
        json.dump(out_arr, self)