Man pages matching name gnutls_pkcs7_get_signature_count in section 3:

gnutls_pkcs7_get_signature_count.3.en	debian 10 / gnutls-doc
gnutls_pkcs7_get_signature_count.3.en	debian 11 / gnutls-doc
gnutls_pkcs7_get_signature_count.3.en	debian 12 / gnutls-doc