@deftypefun {int} {gnutls_heartbeat_pong} (gnutls_session_t @var{session}, unsigned int @var{flags})
@var{session}: is a @code{gnutls_session_t} type.
@var{flags}: should be zero
This function replies to a ping by sending a pong to the peer.
@strong{Returns:} @code{GNUTLS_E_SUCCESS} on success, otherwise a negative error code.
@strong{Since:} 3.1.2
@end deftypefun