Stuff

static void
see_segment(double x, double y, double z, double a, double b, double c) {
    bool changed_abc = (a != canonEndPoint.a)
        || (b != canonEndPoint.b)
        || (c != canonEndPoint.c);
    
    if(!chained_points().empty() && !linkable(x, y, z, a, b, c)) {
        flush_segments();
    }
    pt pos = {x, y, z, a, b, c, interp_list.get_next_line_number()};
    chained_points().push_back(pos);
    if(changed_abc) {
        flush_segments();
    }
}