Go appending elements to slice of struct

I'm trying to append elements to a slice of a struct but it's returning error invalidAppend, that means that the first argument I'm passing is not a slice.

Link to Go Playground.

Here's the code:

type Item struct {
  Attr string
}
type ItemsList []Item
type IItemsList interface {
  GetItemsList() ItemsList
  AddItem(Item)
}
func NewItemsList() IItemsList {
  return &ItemsList{}
}
func (il *ItemsList) GetItemsList() ItemsList {
  return *il
}
func (il *ItemsList) AddItem(i Item) {
  il = append(il, i)
}

I can't figure how is the correct way to proceed with this append.

> the first argument I'm passing is not a slice

The first argument is a pointer to a slice.

type ItemsList []Item
func (il *ItemsList) AddItem(i Item) {
  il = append(il, i)
}

The first argument is a slice.

func (il *ItemsList) AddItem(i Item) {
	*il = append(*il, i)
}

https://go.dev/play/p/Se2ZWcucQOp

> The Go Programming Language Specification
>
> Address operators
>
> For an operand x of pointer type *T, the pointer indirection *x denotes the variable of type T pointed to by x.