class interface HELP_STRING creation feature(s) from HELP_STRING help: STRING set_help (s: STRING) -- Set help string. require valid_string: s /= Void ensure keep_reference: help = s make (s: STRING) -- Set help string. require valid_string: s /= Void ensure keep_reference: help = s copy_help_to (other: HELP_STRING) -- Copy from other. require valid: other /= Void ensure keep_reference: other.help = help invariant valid_help: help /= Void; end of HELP_STRING