Write a recursive method called sumTo that accepts an integer parameter n and returns a real number representing the sum of the
first n reciprocals. In other words, sumTo(n) returns (1 1/2 1/3 1/4 ... 1/n). For example, sumTo(2) should return 1.5. The method should return 0.0 if it is passed the value 0 and throw an IllegalArgumentException if it is passed a value less than 0.
