Main client entrypoint into the authentication APIs: clients are expected to invoke this func with a context containing a login provider name value.

Return the name of the login provider specified in this context, or empty string if none.

Return the name of the login provider specified in this context.

Register an authentication provider (aka "login provider").

Return a context that inherits all values from the parent ctx and specifies the login provider name given here.

Authentication was attempted and failed (likely due to incorrect credentials, too many retries within a time window, etc).

No login provider name has been specified in a context.Context.

SPI interface: login provider implementations support this interface, clients do not authenticate against this directly, instead they should use Login().

Func adapter for interface: allow func's to implement the Authenticatee interface as long as the func signature matches.