+Prompting with string PROMPT.
+If the user enters null input, return second argument DEFAULT-CODING-SYSTEM.
+DEFAULT-CODING-SYSTEM can be a string, symbol, or coding-system object."
+ (intern (completing-read prompt obarray 'find-coding-system t nil nil
+ (cond ((symbolp default-coding-system)
+ (symbol-name default-coding-system))
+ ((coding-system-p default-coding-system)
+ (symbol-name (coding-system-name default-coding-system)))
+ (t
+ default-coding-system)))))