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: backend_find.go
    path of file: ./repos/restic/internal/restic
    
    the code of the file until where you have to start completion: package restic

import (
	"context"
	"fmt"
)

// A MultipleIDMatchesError is returned by Find() when multiple IDs with a
// given prefix are found.
type MultipleIDMatchesError struct{ prefix string }

func (e *MultipleIDMatchesError) Error() string {
	return fmt.Sprintf("multiple IDs with prefi
    
func Find(ctx context.Context, be Lister, t FileType, prefix string) (ID, error) {
	match := ID{}

	ctx, cancel := context.WithCancel(ctx)
	defer cancel()

	err := be.List(ctx, t, func(id ID, _ int64) error {
		name := id.String()
		if len(name) >= len(prefix) && prefix == name[:len(prefix)] {
			if match.IsNull() {
				match = id
			} else {
				return &MultipleIDMatchesError{prefix}
			}
		}

		return nil
	})

	if err != nil {
		return ID{}, err
	}

	if !match.IsNull() {
		return match, nil
	}

	return ID{}, &NoIDByPrefixError{prefix}
}