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: query.go
    path of file: ./repos/learning/golang/practice/go-crontab/gopath/src/github.com/mongodb/mongo-go-driver/core/wiremessage
    
    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 f
    
func (q *Query) UnmarshalWireMessage(b []byte) error {
	var err error
	q.MsgHeader, err = ReadHeader(b, 0)
	if err != nil {
		return err
	}
	if len(b) < int(q.MsgHeader.MessageLength) {
		return Error{Type: ErrOpQuery, Message: "[]byte too small"}
	}

	q.Flags = QueryFlag(readInt32(b, 16))
	q.FullCollectionName, err = readCString(b, 20)
	if err != nil {
		return err
	}
	pos := 20 + len(q.FullCollectionName) + 1
	q.NumberToSkip = readInt32(b, int32(pos))
	pos += 4
	q.NumberToReturn = readInt32(b, int32(pos))
	pos += 4

	var size int
	var wmerr Error
	q.Query, size, wmerr = readDocument(b, int32(pos))
	if wmerr.Message != "" {
		wmerr.Type = ErrOpQuery
		return wmerr
	}
	pos += size
	if pos < len(b) {
		q.ReturnFieldsSelector, size, wmerr = readDocument(b, int32(pos))
		if wmerr.Message != "" {
			wmerr.Type = ErrOpQuery
			return wmerr
		}
		pos += size
	}

	return nil
}