code: func OptionExtraHost(name string, IP string) SandboxOption {
  	return func(sb *sandbox) {
  		sb.config.extraHosts = append(sb.config.extraHosts, extraHost{name: name, IP: IP})
  	}
  }
docs: // OptionExtraHost function returns an option setter for extra /etc/hosts options
  // which is a name and IP as strings.