how to get apr_pool_t when need to call ap_md5

[eeadev dev <eeadev@xxxxxxxxx>]

In my function I need to get the checksum using md5.

I saw that there is this function ap_md5(apr_pool_t *a, const unsigned char *string);

but it needs apr_pool_t

how can I get it?

char key[] = "abc";

key_md5 = ap_md5(mem_pool, key);