method KeyStack.prototype.signimport { KeyStack } from "https://deno.land/x/oak@v12.5.0/deps.ts"; sign(data: Data): Promise<string>Take data and return a SHA256 HMAC digest that uses the current 0 index of the keys passed to the constructor. This digest is in the form of a URL safe base64 encoded string. Parametersdata: DataReturnsPromise<string>