public static <T> ToDouble<T> multiply(ToDouble<T> first, ToDouble<T> second) {
        return MultiplyUtil.doubleMultiplyDouble(first, second);
    }
Creates and returns an expression that takes the result of the two
expressions and computes the product.

@param first   the first input expression
@param second  the second input expression
@param <T>     the input type
@return        the new expression
runtime-parent/runtime-compute/src/main/java/com/speedment/runtime/compute/expression/Expressions.java