static bool line_begins(const char *s, size_t m, const char *word) {
        const char *p;

        p = memory_startswith(s, m, word);
        return p && (p == (s + m) || *p == ' ');
}
static bool line_begins(const char *s, size_t m, const char *word) {
        const char *p;

        p = memory_startswith(s, m, word);
        return p && (p == (s + m) || *p == ' ');
}