Function for "existKey" - Async function - Documentation

[Simone4e]

Good morning everyone,

I would like to ask since there is no documentation on the use but only general of the functions why these functions do not exist:

• Function for "existKey":
  I don't see a function to understand if the secret key that then allows the server to log in the user is present or not, if it were present I could decide whether to show the fingerprint at startup or not

• Async function:
  In the tutorial of the old plugin async is used which is very useful for better managing the system, I see that at the moment there is only the callback as a possibility.

• Documentation:
  It would be nice to have a practical use documentation with some examples, for example my idea was:
  User xx logs into the app for the first time, uses the credentials already provided to log into the app regularly, at which point if the Fingerprint is available, I register the fingerprint with a special token that comes from the login request.
  Now every time the person enters the app instead of using username/password he will use the Fingerprint which will then be compared with the server string === string