How to write Trigraph like character sequences in a string (was: Re: to "OR" or not to "OR")

[Steven Parkes]

|> >puts("               4) ??\!");

|> >2) and 3) should work OK, [...] I'm not quite sure about 4)

|> It works.

(4) is not guaranteed to work because '\!' is not a valid ANSI escape.  The
result of using '\!' (or any other invalid escape sequence) is undefined.