package main

import "fmt"

type calc struct {
	value int
}

func (c calc) add(n int) calc {
	c.value = c.value + n
	return c
}

func (c calc) sub(n int) calc {
	c.value = c.value - n
	return c
}

func (c calc) mul(n int) calc {
	c.value = c.value * n
	return c
}

func (c calc) show() {
	fmt.Printf("Value: %d\n", c.value)
}

func main() {
	total := calc{}

	total = total.add(10)
	total.show() // Value: 10

	total = total.mul(3)
	total.show() // Value: 30

	total = total.sub(5)
	total.show() // Value: 25
}