*. The reflected Gray code of order $n$ is properly called the reflected binary Gray code since it is a listing of the $n$ -tuples of $0 \mathrm{~s}$ and 1 s. It can be generalized to any base system, in particular the ternary and decimal system. Thus, the reflected decimal Gray code of order $n$ is a listing of all the decimal numbers of $n$ digits such that consecutive numbers in the list differ in only one place and the absolute value of the difference is $1 .$ Determine the reflected decimal Gray codes of orders 1 and 2 . (Note that we have not said precisely what a reflected decimal Gray code is. Part of the problem is to discover what it is.) Also, determine the reflected ternary Gray codes of orders 1,2 , and 3 .