Write a simplify(self) method that replaces the polynomial's internal representation with an equivalent, simplified representation. Unlike the previous methods, simplify(self) does not return a new polynomial, but rather acts in place. However, because the fundamental character of the polynomial is not changing, we do not consider this to violate the notion that polynomials are immutable. The simplification process should begin by combining terms with a common power. Then, terms with a coefficient of zero should be removed, and the remaining terms should be sorted in decreasing order based on their power. In the event that all terms have a coefficient of zero after the first step, the polynomial should be simplified to the single term 0