package main import ( "flag" "fmt" "time" ) func main() { var durationFlag time.Duration fs := flag.NewFlagSet("ExampleFlagSetDuration", flag.ContinueOnError) // Add the duration flag with a default value fs.DurationVar(&durationFlag, "duration", 10*time.Second, "the duration of the operation in seconds") // Parse the command-line arguments err := fs.Parse([]string{"--duration=5s"}) if err != nil { fmt.Println("Error parsing flags:", err) } // Print out the value of the duration flag fmt.Println("Duration flag value:", durationFlag) }This example sets a default value of 10 seconds for the "-duration" flag and then parses the command-line argument "-duration=5s". It then prints the resulting value of the "durationFlag" variable. The package library for the FlagSet Duration feature is the standard "flag" package that comes with Go.