Pasted

type Shape interface {
    area() float64
}
 
type Rectangle struct{
    height float64
    width float64
}
 
type Circle struct{
    radius float64
}
 
func (r Rectangle) area() float64 {
    return r.height * r.width
}
 
func (c Circle) area() float64 {
    return math.Pi * math.Pow(c.radius, 2)
}