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: prune.go
    path of file: ./repos/sealer/vendor/github.com/ostreedev/ostree-go/pkg/otbuiltin
    
    the code of the file until where you have to start completion: package otbuiltin

import (
	"bytes"
	"errors"
	"strconv"
	"strings"
	"time"
	"unsafe"

	glib "github.com/ostreedev/ostree-go/pkg/glibobject"
)

// #cgo pkg-config: ostree-1
// #include <stdlib.h>
// #include <glib.h>
// #include <ostree.h>
// #include "builtin.go.h"
import "C"

// Declare gobal variable for options
var pruneOpts pruneOptions

// Contains all of the options for pruning an ostree repo.  Use
// NewPruneOptions() to initialize
type pruneOptions struct {
	NoPrune          bool      // Only display unreachable objects; don't delete
	RefsOnly         bool      // Only compute reachability via refs
	DeleteCommit     string    // Specify a commit to delete
	KeepYoungerThan  time.Time // All commits older than this date will be pruned
	Depth            int       // Only traverse depths (integer) parents for each commit (default: -1=infinite)
	StaticDeltasOnly int       // Change the behavior of --keep-younger-than and --delete-commit to prune 
    
func pruneCommitsKeepYoungerThanDate(repo *Repo, date time.Time, cancellable *glib.GCancellable) error {
	var objects *glib.GHashTable
	defer C.free(unsafe.Pointer(objects))
	var hashIter glib.GHashTableIter
	var key, value C.gpointer
	defer C.free(unsafe.Pointer(key))
	defer C.free(unsafe.Pointer(value))
	var gerr = glib.NewGError()
	var cerr = (*C.GError)(gerr.Ptr())
	defer C.free(unsafe.Pointer(cerr))

	if err := repo.enableTombstoneCommits(); err != nil {
		return err
	}

	if !glib.GoBool(glib.GBoolean(C.ostree_repo_list_objects(repo.native(), C.OSTREE_REPO_LIST_OBJECTS_ALL, (**C.GHashTable)(objects.Ptr()), (*C.GCancellable)(cancellable.Ptr()), &cerr))) {
		return generateError(cerr)
	}

	C.g_hash_table_iter_init((*C.GHashTableIter)(hashIter.Ptr()), (*C.GHashTable)(objects.Ptr()))
	for C.g_hash_table_iter_next((*C.GHashTableIter)(hashIter.Ptr()), &key, &value) != 0 {
		var serializedKey *glib.GVariant
		defer C.free(unsafe.Pointer(serializedKey))
		var checksum *C.char
		defer C.free(unsafe.Pointer(checksum))
		var objType C.OstreeObjectType
		var commitTimestamp uint64
		var commit *glib.GVariant = nil

		C.ostree_object_name_deserialize((*C.GVariant)(serializedKey.Ptr()), &checksum, &objType)

		if objType != C.OSTREE_OBJECT_TYPE_COMMIT {
			continue
		}

		cerr = nil
		if !glib.GoBool(glib.GBoolean(C.ostree_repo_load_variant(repo.native(), C.OSTREE_OBJECT_TYPE_COMMIT, checksum, (**C.GVariant)(commit.Ptr()), &cerr))) {
			return generateError(cerr)
		}

		commitTimestamp = (uint64)(C.ostree_commit_get_timestamp((*C.GVariant)(commit.Ptr())))
		if commitTimestamp < (uint64)(date.Unix()) {
			cerr = nil
			if pruneOpts.StaticDeltasOnly != 0 {
				if !glib.GoBool(glib.GBoolean(C.ostree_repo_prune_static_deltas(repo.native(), checksum, (*C.GCancellable)(cancellable.Ptr()), &cerr))) {
					return generateError(cerr)
				}
			} else {
				if !glib.GoBool(glib.GBoolean(C.ostree_repo_delete_object(repo.native(), C.OSTREE_OBJECT_TYPE_COMMIT, checksum, (*C.GCancellable)(cancellable.Ptr()), &cerr))) {
					return generateError(cerr)
				}
			}
		}
	}

	return nil
}