What does this function return if line is empty?
int is_comment_or_empty(const char *line) {
    for (int i = 0; i < strlen(line); i++) {
        if (line[i] == '#') {
            return 1;
        }
        if (line[i] != '\t' && line[i] != ' ') {
            return 0;
        }
    }
    return 1;
}