struct feer_conn * T_feer_conn
feer_conn_handle * T_feer_conn_handle

INPUT
T_feer_conn
    $var = sv_2feer_conn($arg);

T_feer_conn_handle
    SV *hdl_sv = SvRV($arg);
    $var = sv_2feer_conn_handle($arg,1);
    /* handle is really just a feer_conn struct: */
    struct feer_conn *c = (struct feer_conn *)$var;

OUTPUT
T_feer_conn
   $arg = feer_conn_2sv($var);