anchor.diff:  -spec disconnect(pid()) -> ok.
   -spec insert(pid(), colldb(), A) -> A | { error, reason() }.
   -spec update(pid(), colldb(), selector(), bson:document()) -> ok | { error, reason() }.
  +-spec update(pid(), colldb(), selector(), bson:document(), proplists:proplist()) -> ok | { error, reason() }.
   -spec delete(pid(), colldb(), selector()) -> ok | { error, reason() }.
   -spec delete_one(pid(), colldb(), selector()) -> ok | { error, reason() }.
   -spec find_one(pid(), colldb(), selector()) -> {} | {bson:document()}.
  
positive.code: %% @doc Inserts a document or multiple documents into a collection.
  %%      Returns the document or documents with an auto-generated _id if missing.
  
  insert( Topology, Coll, Doc ) when is_tuple(Doc); is_map(Doc) ->
  	case mc_topology:get_pool( Topology, [{rp_mode, primary}] ) of
  		{ ok, #{ pool := C } } ->
  			try	mongo:insert( C, Coll, Doc ) of
  
negative.code: 
  %% @doc Replaces the document matching criteria entirely with the new Document.
  
  update( Topology, Coll, Selector, Doc ) ->
  	update( Topology, Coll, Selector, Doc, [] ).
  
  update( Topology, Coll, Selector, Doc, Options ) ->
  	case mc_topology:get_pool( Topology, [{rp_mode, primary}] ) of
  		{ ok, #{ pool := C } } ->
  			try	mongo:update( C, Coll, Selector, Doc, Options) of
  				R -> R
  			catch
  				error:not_master ->
  