TypeScript: TypeScript declare a type that can be a string or array of strings

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Simple one, but I forgot the exact syntax and had to search for it, so let me write it:

export interface Props {
  tag: string | string[]
}

tag can be a string, or an array of strings

Lessons in this unit:

0: Introduction
1: Your first TypeScript program
2: Types
3: Typing functions
4: The editor helps you with type errors
5: Running TypeScript code
6: Valid types
7: Type aliases and interfaces
8: Union types
9: Typing arrays with generics
10: The DX of editing TypeScript
11: There's more...
12: ▶︎ TypeScript declare a type that can be a string or array of strings
13: TypeScript, disable checks for `declared but its value is never read`
14: Object destructuring with types in TypeScript
15: TypeScript Tutorial
16: Zod: Type-Safe Schema Validation for TypeScript
17: How I fixed some trouble importing types in .d.ts files