-  get_key(+Valid:list(char), -C:char) is det
 - Get and validate a key press from the user. The character
must be one of the ones listed in Valid, otherwise, an
error message is printed and the user prompted again.
 
-  userchk(T) is semidet
 - Write T and ask this user if it is ok. User presses y or n.
userchk succeeds if if the keypress was y and fails if it was n.
 
-  termcap(-Cap:atom, -Type:atom) is nondet
 - Extracts two character termcap capabilities and types from TERMCAP environment variable.
These can be used with tty_get_capability/3.
 
Undocumented predicates
The following predicates are exported, but not or incorrectly documented.
-  with_status_line(Arg1)
 
-  put_cap(Arg1, Arg2)
 
-  put_cap(Arg1)
 
-  status(Arg1, Arg2)
 
-  msg(Arg1, Arg2)
 
-  msg(Arg1)
 
-  heading(Arg1, Arg2)
 
-  ask(Arg1, Arg2, Arg3)