char *
ft_substr(char const *s, u32 start, size_t len) {
	i64	size;
	char	*new_s;

	if (s == NULL)
		return (NULL);
	size = ft_strlen(s) - start;
	if (size < 0)
		size = 0;
	else if ((u64)size > len)
		size = len;
	new_s = ft_calloc(size + 2, 1);
	if (new_s == NULL)
		return (NULL);
	if (start <= ft_strlen(s))
		ft_strlcpy(new_s, s + start, len + 1);
	else
		new_s[0] = '\0';
	return (new_s);
}