code: func Host(host string) {
  	if !hostnameRegex.MatchString(host) {
  		dslengine.ReportError(`invalid hostname value "%s"`, host)
  		return
  	}
  
  	if a, ok := apiDefinition(); ok {
  		a.Host = host
  	}
  }
docs: // Host used in: API
  //
  // Host sets the API hostname.