title: What is the definition of "Symbol" in the context of typescript compiler API?
body: <p>I am looking for the definition and examples of the term "<a href="https://github.com/microsoft/TypeScript/blob/d7c83f023eeb16027c5942b8156207e9f068b367/src/compiler/types.ts#L3774" rel="nofollow noreferrer">Symbol</a>" in the context of the typescript compiler API. </p>
  
  <ul>
  <li>how is it constructed? </li>
  <li>what is it used for? </li>
  </ul>
  
  <p>Thank you!</p>