refactor union, unique, except and merge
refactor union, unique, except and merge

mcanthony/enyo,beni55/enyo,bright-sparks/enyo,airspringsoftware/enyo,wikieswan/enyo,enyojs/enyo,bright-sparks/enyo,PKRoma/enyo,soapdog/enyo,mcanthony/enyo,zefsolutions/enyo,airspringsoftware/enyo,enyojs/enyo,wikieswan/enyo,kustomzone/enyo,kustomzone/enyo,soapdog/enyo,PKRoma/enyo,zefsolutions/enyo,beni55/enyo