Write a function playExpert(marbles) that given a number of marbles returns the number of marbles that the computer will take following the expert mode rules. The number of marbles left on the pile will be a power of 2 minus 1 (e.g, 3, 7, 31) except if the size of the pile is already one less than the power of 2. In that case the computer will return a random number of marbles.
>>> playExpert(90)
27 (if computer takes 27 there will 90-27= 63 (26-1) marbles left )
>>playExpert(31) number of marbles a power of 2 minus 1
12
Make sure that your tests show that the function works for both cases.