Circle Package Example with Go

circle.go

package circle

import (
	"math"
)

type Circle struct {
	Radius float64
}

func (c Circle) Diameter() float64 {
	return 2 * c.Radius
}

func (c Circle) Area() float64 {
	return math.Pi * c.Radius * c.Radius
}

func (c Circle) Circumference() float64 {
	return math.Pi * c.Diameter()
}