Down_std.StdinSetup standard input for tty interaction.
Note. When the module is loaded an at_exit handler is installed to make sure set_raw_mode false is called at the end of the program.
set_raw_mode raw sets stdin raw mode according to raw returns false if the operation fails.
enable_bracketed_paste oc enables bracketed paste mode on oc. This is disabled at exit on the same channel via an at_exit handler.