You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: area.go
    path of file: ./repos/web-dev-golang-anti-textbook/code/ObjectOriented/area
    
    the code of the file until where you have to start completion: package main

import (
	"fmt"
	"math"
)

type Rectangle struct {
	width, height float64
}

type Ci
    
func main() {
	r1 := Rectangle{12, 2}
	r2 := Rectangle{9, 4}
	c1 := Circle{10}
	c2 := Circle{25}

	fmt.Println("Area of r1 is: ", r1.area())
	fmt.Println("Area of r2 is: ", r2.area())
	fmt.Println("Area of c1 is: ", c1.area())
	fmt.Println("Area of c2 is: ", c2.area())
}