@spec get_handles(t()) :: [String.t()]

Returns a list of handles from a doc. They may not be all validated.

Call get_validated_handle/1 to get the first validated handle.

@spec get_validated_handle(t()) :: String.t() | nil

Returns first validated handle

@spec labeler_endpoint(t()) :: String.t() | nil

Finds serviceEndpoint for labeler service and returns it if it's present.

@spec pds_endpoint(t()) :: String.t() | nil

Finds serviceEndpoint for PDS service and returns it if it's present.