Why did you use the defer keyword?

The defer keyword in Go is used to postpone the execution of a function until the current function exits. This is useful for releasing resources, closing files, unlocking mutexes, and other cleanup operations.

For example, if you open a file, you can use defer to ensure it gets closed even if an error occurs or the function exits early:

func readFile(filename string) error {
    file, err := os.Open(filename)
    if err != nil {
        return err
    }
    defer file.Close() // Will close when the function exits
    // work with the file
    return nil
}

Thus, defer helps write cleaner and safer code, reducing the likelihood of resource leaks.