模板字面量类型

type World = 'world'
type Greeting = `hello ${World}`
       
type Greeting = "hello world"

type EmailLocaleIDs = 'welcome_email' | 'email_heading'
type FooterLocaleIDs = 'footer_title' | 'footer_sendoff'

type AllLocaleIDs = `${EmailLocaleIDs | FooterLocaleIDs}_id`
         
type AllLocaleIDs = "welcome_email_id" | "email_heading_id" | "footer_title_id" | "footer_sendoff_id"