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: doc_map_test.go
    path of file: ./repos/gnark/std/selector
    
    the code of the file until where you have to start completion: package selector_test

import (
	"fmt"

	"github.com/consensys/gnark-crypto/ecc"
	"github.com/consensys/gnark/backend/groth16"
	"github.com/consensys/gnark/frontend"
	"github.com/consensys/gnark/frontend/cs/r1cs"
	"github.com/consensys/gnark/std/selector"
)

// MapCircuit is a minimal circuit using a selector map.
type MapCircuit struct {
	QueryKey      frontend.Variable
	Keys          [10]frontend.Variable // we use array in witness to allocate sufficiently sized vector
	Values        [10]frontend.Variable // we use array in witness to allocate sufficiently sized vector
	ExpectedValue frontend.Variable
}

// Define defines the arithmetic circuit.
func (c *MapCircuit) Define(api frontend.API) error {
	result := selector.Map(api, c.QueryKey, c.Keys[:], c.Values[:])
	api.AssertIsEqual(result, c.ExpectedValue)
	return nil
}

// Example
    
func ExampleMap() {
	circuit := MapCircuit{}
	witness := MapCircuit{
		QueryKey:      55,
		Keys:          [10]frontend.Variable{0, 11, 22, 33, 44, 55, 66, 77, 88, 99},
		Values:        [10]frontend.Variable{0, 2, 4, 6, 8, 10, 12, 14, 16, 18},
		ExpectedValue: 10, // element in values which corresponds to the position of 55 in keys
	}
	ccs, err := frontend.Compile(ecc.BN254.ScalarField(), r1cs.NewBuilder, &circuit)
	if err != nil {
		panic(err)
	}
	pk, vk, err := groth16.Setup(ccs)
	if err != nil {
		panic(err)
	}
	secretWitness, err := frontend.NewWitness(&witness, ecc.BN254.ScalarField())
	if err != nil {
		panic(err)
	}
	publicWitness, err := secretWitness.Public()
	if err != nil {
		panic(err)
	}
	proof, err := groth16.Prove(ccs, pk, secretWitness)
	if err != nil {
		panic(err)
	}
	err = groth16.Verify(proof, vk, publicWitness)
	if err != nil {
		panic(err)
	}
	fmt.Println("done")
	// Output: done
}