After using sock_init() where can I find the parameter for sock_close(&?)

I am opening a smtp socket with sock_init and tries to use sock_close(?) after the e-mail has been tranfered.
The compiler requires a parameter for sock_close(?)
How will I find this? Example code SMTP_TLS.C were I put in sock_init() instead of sock_init_or_exit(1) and then sock_close(&?) in the end.

You will close whatever socket you opened. See an example in serialexa.c

For instance, you declare

tcp_Socket socket;

You open it with


and close with