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: common_options.go
    path of file: ./repos/mongo-go-driver/mongo/integration/unified
    
    the code of the file until where you have to start completion: // Copyright (C) MongoDB, Inc. 2017-present.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License. You may obtain
// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0

package unified

import (
	"fmt"
	"time"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo/readconcern"
	"go.mongodb.org/mongo-driver/mongo/readpref"
	"go.mongodb.org/mongo-drive
    
func (rp *ReadPreference) ToReadPrefOption() (*readpref.ReadPref, error) {
	mode, err := readpref.ModeFromString(rp.Mode)
	if err != nil {
		return nil, fmt.Errorf("invalid read preference mode %q", rp.Mode)
	}

	var rpOptions []readpref.Option
	if rp.TagSets != nil {
		// Each item in the TagSets slice is a document that represents one set.
		sets := make([]tag.Set, 0, len(rp.TagSets))
		for _, rawSet := range rp.TagSets {
			parsed := make(tag.Set, 0, len(rawSet))
			for k, v := range rawSet {
				parsed = append(parsed, tag.Tag{Name: k, Value: v})
			}
			sets = append(sets, parsed)
		}

		rpOptions = append(rpOptions, readpref.WithTagSets(sets...))
	}
	if rp.MaxStalenessSeconds != nil {
		maxStaleness := time.Duration(*rp.MaxStalenessSeconds) * time.Second
		rpOptions = append(rpOptions, readpref.WithMaxStaleness(maxStaleness))
	}
	if rp.Hedge != nil {
		if len(rp.Hedge) > 1 {
			return nil, fmt.Errorf("invalid read preference hedge document: length cannot be greater than 1")
		}
		if enabled, ok := rp.Hedge["enabled"]; ok {
			rpOptions = append(rpOptions, readpref.WithHedgeEnabled(enabled.(bool)))
		}
	}

	return readpref.New(mode, rpOptions...)
}