inserts swap() function in a header of a class.
inserts swap() function in a header of a class.

hiroyuki-seki/hryky-codebase,hiroyuki-seki/hryky-codebase,hiroyuki-seki/hryky-codebase,hiroyuki-seki/hryky-codebase,hiroyuki-seki/hryky-codebase,hiroyuki-seki/hryky-codebase