int cvCheckContourConvexity(CvArr* contour) {
    void *fptr;
    int retval;

    fptr = dlsym(_Chcv_handle, "cvCheckContourConvexity_chdl");
    if(fptr == NULL) {
        fprintf(_stderr, "Error: %s(): dlsym(): %s\n", __func__,  dlerror());
        return -1;
    }
    dlrunfun(fptr, &retval, cvCheckContourConvexity, contour);
    return retval;
}
