https://go.dev/tour/generics/2

generics 2.go

package main

import "fmt"

// List represents a singly-linked list that holds
// values of any type.
type List[T comparable] struct {
	next *List[T]
	val  T
}

type ListError struct {
	msg string
}

func (e ListError) Error() string {
	return "List Error" 
}

func (self *List[T]) find(val T) (T, error){
	item := self
	for item != nil {
		if item.val == val {
			return item.val, nil
		}
		item = item.next
	}
	return val, ListError{"Item not found"}
}

func main() {
	list := List[int]{&List[int]{nil, 2}, 1}
	
	val, _ := list.find(1)
	fmt.Println(val)

	val1, _ := list.find(2)
	fmt.Println(val1)

	val2, err := list.find(3)
	
	fmt.Println(err, val2)

}