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: keys.go
    path of file: ./repos/cds/engine/gorpmapper
    
    the code of the file until where you have to start completion: package gorpmapper

import (
	"encoding/json"

	// Import all symmecrypt ciphers
	_ "github.com/ovh/symmecrypt/ciphers/aesgcm"
	_ "git
    
func (m *Mapper) ConfigureKeys(signatureKeys, encryptionKeys *[]keyloader.KeyConfig) error {
	var globalErr error
	m.once.Do(func() {
		// Marshal the keys
		var marshalledKeys [][]byte
		for _, k := range *signatureKeys {
			btes, err := json.Marshal(k)
			if err != nil {
				globalErr = sdk.WithStack(err)
				return
			}
			marshalledKeys = append(marshalledKeys, btes)
		}
		for _, k := range *encryptionKeys {
			btes, err := json.Marshal(k)
			if err != nil {
				globalErr = sdk.WithStack(err)
			}
			marshalledKeys = append(marshalledKeys, btes)
		}

		store := configstore.NewStore()

		var provider configstore.Provider
		provider = func() (configstore.ItemList, error) {
			list := configstore.ItemList{}
			for _, btes := range marshalledKeys {
				list.Items = append(list.Items, configstore.NewItem(keyloader.EncryptionKeyConfigName, string(btes), 99))
			}
			return list, nil
		}
		store.RegisterProvider("fakeConfigstoreProvider", provider)

		var err error
		m.signatureKey, err = keyloader.WatchKeyFromStore(KeySignIdentifier, store)
		if err != nil {
			globalErr = sdk.WithStack(err)
		}

		m.encryptionKey, err = keyloader.WatchKeyFromStore(KeyEcnryptionIdentifier, store)
		if err != nil {
			globalErr = sdk.WithStack(err)
		}
	})

	return globalErr
}