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: append_test.go
    path of file: ./repos/ferret/pkg/stdlib/arrays
    
    the code of the file until where you have to start completion: package arrays_test

import (
	"context"
	"testing"

	. "github.com/smartystreets/goconvey/convey"

	"github.com/MontFerret/ferret/pkg/runtime/collections"
	"github.com/MontFerret/ferret/pkg/runtime/values"
	"github.com/MontFerret/ferret/pkg/stdlib/arrays"
)

func TestAppend(t *testing.T) {
	Convey("Should return a copy of an array", t, func() {
		arr := values.NewArrayWith(
			values.NewInt(1),
			values.NewInt(2),
			values.NewInt(3),
			values.NewInt(4),
			values.NewInt(5),
		)

		out,
    
func TestAppend(t *testing.T) {
	Convey("Should return a copy of an array", t, func() {
		arr := values.NewArrayWith(
			values.NewInt(1),
			values.NewInt(2),
			values.NewInt(3),
			values.NewInt(4),
			values.NewInt(5),
		)

		out, err := arrays.Append(context.Background(), arr, values.NewInt(6))

		So(err, ShouldBeNil)
		So(out, ShouldNotEqual, arr)
		So(out.(collections.Measurable).Length(), ShouldBeGreaterThan, arr.Length())
	})

	Convey("Should ignore non-unique items", t, func() {
		arr := values.NewArrayWith(
			values.NewInt(1),
			values.NewInt(2),
			values.NewInt(3),
			values.NewInt(4),
			values.NewInt(5),
		)

		out, err := arrays.Append(context.Background(), arr, values.NewInt(5), values.True)

		So(err, ShouldBeNil)
		So(out, ShouldNotEqual, arr)
		So(out.(collections.Measurable).Length(), ShouldEqual, arr.Length())

		out2, err := arrays.Append(context.Background(), arr, values.NewInt(6), values.True)

		So(err, ShouldBeNil)
		So(out2, ShouldNotEqual, arr)
		So(out2.(collections.Measurable).Length(), ShouldBeGreaterThan, arr.Length())
	})
}