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: manifold.go
    path of file: ./repos/juju/worker/presence
    
    the code of the file until where you have to start completion: // Copyright 2018 Canonical Ltd.
// Licensed under the AGPLv3, see LICENCE file for details.

package presence

import (
	"github.com/juju/errors"
	"github.com/juju/pubsub/v2"
	"github.com/juju/worker/v3"
	"github.com/juju/worker/v3/dependency"

	coreagent "github.com/juju/juju/agent"
	"github.com/juju/juju/core/presence"
)

// Logger represents the logging methods called.
type Logger interface {
	Errorf(message string, args ...interface{})
	Infof(message string, args ...interface{})
	Debugf(message string, args ...interface{})
	Tracef(mess
    
func Manifold(config ManifoldConfig) dependency.Manifold {
	return dependency.Manifold{
		Inputs: []string{
			config.AgentName,
			config.CentralHubName,
		},
		Start: func(context dependency.Context) (worker.Worker, error) {
			if err := config.Validate(); err != nil {
				return nil, err
			}
			// Get the agent.
			var agent coreagent.Agent
			if err := context.Get(config.AgentName, &agent); err != nil {
				config.Logger.Tracef("agent dependency not available")
				return nil, err
			}
			origin := agent.CurrentConfig().Tag().String()

			// Get the hub.
			var hub *pubsub.StructuredHub
			if err := context.Get(config.CentralHubName, &hub); err != nil {
				config.Logger.Tracef("hub dependency not available")
				return nil, err
			}
			config.Recorder.Enable()

			cfg := WorkerConfig{
				Origin:   origin,
				Hub:      hub,
				Recorder: config.Recorder,
				Logger:   config.Logger,
			}
			return config.NewWorker(cfg)
		},
	}
}