@deftypefun {int} {gnutls_x509_tlsfeatures_add} (gnutls_x509_tlsfeatures_t @var{f}, unsigned int @var{feature})
@var{f}: The TLS features

@var{feature}: The feature to add

This function will append a feature to the X.509 TLS features
extension structure.

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned,
otherwise a negative error value.

@strong{Since:} 3.5.1
@end deftypefun