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: filter.go
    path of file: ./repos/sealer/vendor/github.com/multiformats/go-multiaddr
    
    the code of the file until where you have to start completion: package multiaddr

import (
	"net"
	"sync"
)

// Action is an enum modelling all possible filter actions.
type Action int32

const (
	Actio
    
func (fs *Filters) AddFilter(ipnet net.IPNet, action Action) {
	fs.mu.Lock()
	defer fs.mu.Unlock()

	if _, f := fs.find(ipnet); f != nil {
		f.action = action
	} else {
		fs.filters = append(fs.filters, &filterEntry{ipnet, action})
	}
}