method OutgoingMessage.prototype.appendHeader
Usage in Deno
```typescript import { OutgoingMessage } from "node:node__http.d.ts"; ```
OutgoingMessage.prototype.appendHeader(name: string,value: string | readonly string[],): this
Append a single header value to the header object.
If the value is an array, this is equivalent to calling this method multiple
times.
If there were no previous values for the header, this is equivalent to calling `outgoingMessage.setHeader(name, value)`.
Depending of the value of `options.uniqueHeaders` when the client request or the
server were created, this will end up in the header being sent multiple times or
a single time with values joined using `; `.
this