Pointer in Go (Checkout this gist whenever you forget the concept of pointers in Go)

pointers.go

package main

import "fmt"

func main() {
        i, j := 42, 2701
        fmt.Println(i, j)
        fmt.Println(&i, &j)

        // you can read "&i" as "address of i"
        p := &i
        // var p *int
        // here, p's type is "pointer pointing to integers"
        fmt.Printf("%T\n", p)
        // *p
        // here, * is an operator that returns what p is pointing to
        // it is also called "dereferencing"
        fmt.Println(*p)
        // changing value of *p will change the value of i
        *p = 21
        fmt.Println(i)

        p = &j
        *p = *p / 37
        fmt.Println(j)

        // this function call mutates the value of i
        squareVal(&i)
        fmt.Println(i)
}

func squareVal(p *int) {
        *p *= *p
        // so, return a pointer or a value? up to ya! if you return a pointer, the Go garbage collector will have something more todo with the heap. just focus on readibility for now!!
        fmt.Println(p, *p)
}