input: Write a python function to evaluate a polynomial at a given x value.
  assert Polynomial([2, 3, 0, 5]).evaluate(1) == 10
  assert Polynomial([1, 0, 3, 2]).evaluate(2) == 17
  assert Polynomial([4, 0, -2, 1]).evaluate(3) == 25
output: class Polynomial:
      def __init__(self, coefficients):
          self.coefficients = coefficients
  
      def evaluate(self, x):
          result = 0
          for power, coeff in enumerate(self.coefficients):
              result += coeff * (x ** power)
          return result