Represent a polynomial using a list of its (real) coefficients, starting with the constant coefficient and going only as high as necessary. For example, 3x^2+5x+1 would be represented as the list [1.0 5.0 3.0] and x^3-2x as [0.0 -2.0 0.0 1.0]. Write a function poly of type real list * real -> real that takes a polynomial represented this way and returns the value of the polynomial at the given x. For example poly ([1.0 5.0 3.0],2.0) should evaluate to 23.0, because when x=2, 3x2+5x+1=23.