CV_SET_ELEM_FREE_FLAG 1757 modules/core/include/opencv2/core/core_c.h     _elem->flags = (_elem->flags & CV_SET_ELEM_IDX_MASK) | CV_SET_ELEM_FREE_FLAG;
CV_SET_ELEM_FREE_FLAG 2515 modules/core/src/datastructs.cpp             ((CvSetElem*)ptr)->flags = count | CV_SET_ELEM_FREE_FLAG;