improve Group#members code
improve Group#members code

stan/shapado,ricodigo/shapado,gravityrail/shapado,sinnerex/zoorab,NazarK/shapado,sinnerex/zoorab,ooohiroyukiooo/shapado,10xEngineer/shapado,gravityrail/shapado,ooohiroyukiooo/shapado,ooohiroyukiooo/shapado,ricodigo/shapado,cctuan/shapado_g,stan/shapado,stan/shapado,ooohiroyukiooo/shapado,cctuan/shapado_g,NazarK/shapado,cctuan/shapado_g,10xEngineer/shapado,amyhua/QnA,sinnerex/zoorab,amyhua/QnA,amyhua/QnA,NazarK/shapado,ricodigo/shapado,stan/shapado,gravityrail/shapado,10xEngineer/shapado