Write a recursive method called doubleDigits that accepts an integer n as a parameter and returns the integer obtained by replacing every digit of n with two of that digit. For example, doubleDigits (348) should return 334488. The call doubleDigits (0) should return 0. Calling doubleDigits on a negative number should return the negation of calling doubleDigits on the corresponding positive number; for example, doubleDigits (- 789) should return - 778899