question: public static byte [ ] concat ( byte [ ] b1 , byte [ ] b2 ) { byte [ ] out = new byte [ b1 . length + b2 . length ] ; System . arraycopy ( b1 , 0 , out , 0 , b1 . length ) ; System . arraycopy ( b2 , 0 , out , b1 . length , b2 . length ) ; return out ; }
target:  Concatenates and returns the given byte arrays.