anchor.diff:  %%% @doc
   %%%     Key manager for AE node
   %%%     * it will open keys that it finds using sys.config
  -%%%     * generating new/1 or setting set/3 keys will fail when another keys are present
   %%%     * delete/0 removes files from the filesystem and from the state (DANGER!)
   %%% @end
   %%% Created : 28 Aug 2017
  
positive.code: -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
           terminate/2, code_change/3]).
  
  -export([new/1, set/3, sign/1, pubkey/0, delete/0,
           wait_for_pubkey/0]).
  -export([verify/2]).
  -export([check_key_pair/0]).
  
negative.code:         Err:R ->
              lager:error("New keys not deleted ~p ~p", [Err, R]),
              {reply, error, State}
      end.
  
  handle_cast(_Msg, State) ->
  