https://manpages.ubuntu.com/manpages/xenial/man3/Tcl_CreateCloseHandler.3tcl.html
Ubuntu Manpage: Tcl_CreateCloseHandler, Tcl_DeleteCloseHandler - arrange for callbacks when...
arrange for callbacks when channels are closed
ubuntumanpagetclarrangecallbacks
https://manpages.ubuntu.com/manpages/xenial/man3/Tcl_DeleteCloseHandler.3tcl.html
Ubuntu Manpage: Tcl_CreateCloseHandler, Tcl_DeleteCloseHandler - arrange for callbacks when...
arrange for callbacks when channels are closed
ubuntumanpagetclarrangecallbacks