/* @str: string with prefix @prefix: prefix string Return: string without prefix, or NULL if prefix not found  */
static const char* prefix(const char *str, const char *prefix)
/* @str: string with prefix @prefix: prefix string Return: string without prefix, or NULL if prefix not found  */
static const char* prefix(const char *str, const char *prefix)
{
	size_t n = strlen(prefix);
	if (!strncmp(prefix, str, n))
		return str + n;
	return NULL;
}