i t o r y . a l l # = > [ # < B o o k : 0 x 0 0 7 f 4 d d 7 d 3 c 4 b 8 @ i d = 1 , @ n a m e = " a a " , @ p r i c e = " 1 0 0 " , @ c o d e = " 1 2 3 " B o o k R e p o s i t o r y . a l l . f i r s t # = > # < B o o k : 0 x 0 0 7 f 4 d d 7 d 0 a b 4 8 @ i d = 1 , @ n a m e = " a a " , @ p r i c e = " 1 0 0 " , @ c o d e = " 1 2 3 " n e w _ b o o k = B o o k . n e w ( n a m e : " n e w b o o k " , p r i c e : 1 0 0 0 , a u t h o r _ i d : 1 , c o d e : ' 0 0 0 7 7 ' # = > # < B o o k : 0 x 0 0 7 f 4 d d 7 b b d a b 0 @ n a m e = " n e w b o o k " , @ p r i c e = 1 0 0 0 , @ c o d e = " 0 0 0 7 7 " , B o o k R e p o s i t o r y . c r e a t e ( n e w _ b o o k ) # = > # < B o o k : 0 x 0 0 7 f 4 d d 7 b b 8 f 6 0 @ i d = 5 , @ n a m e = " n e w b o o k " , @ p r i c e = " 1 0 0 0 " , @ c o d e