code: func PortCommand(factory app.ProjectFactory) cli.Command {
  	return cli.Command{
  		Name:   "port",
  		Usage:  "Print the public port for a port binding",
  		Action: app.WithProject(factory, app.ProjectPort),
  		Flags: []cli.Flag{
  			cli.StringFlag{
  				Name:  "protocol",
  				Usage: "tcp or udp ",
  				Value: "tcp",
  			},
  			cli.IntFlag{
  				Name:  "index",
  				Usage: "index of the container if there are multiple instances of a service",
  				Value: 1,
  			},
  		},
  	}
  }
docs: // PortCommand defines the libcompose port subcommand.