anchor.diff:  
   %%--------------------------------------------------------------------
   %% @doc
  -%% Begin a transaction.
  +%% Begin a transaction with default options.
   %%
   %% @spec txn_begin() -> ok | {error, Error}
   %%
  
positive.code: 
  %%--------------------------------------------------------------------
  %% @doc
  %% Returns the next cursor value.
  %%
  %% @spec cursor_next() -> not_found | {ok, Key, Value} | {error, Error}
  %%
  
negative.code: %%--------------------------------------------------------------------
  %% @doc
  %% Close a database file.
  %%
  %% This function flushes any cached database information to disk, closes
  %% any open cursors, frees any allocated resources, and closes any
  %% underlying files.
  %%
  %% The `Db' handle should not be closed while any other handle that refers
  %% to it is not yet closed; for example, database handles must not be
  %% closed while cursor handles into the database remain open, or
  %% transactions that include operations on the database have not yet
  %% been committed or aborted.
  %%
  %% Because key/data pairs are cached in memory, failing to sync the file
  %% with the `close' function may result in inconsistent or lost
  %% information.
  %%
  %% The `Db' handle may not be accessed again after this function is
  %% called, regardless of its return.
  %%
  %% === Options ===
  %%
  %% <dl>
  %%   <dt>no_sync</dt>
  %%   <dd>Do not flush cached information to disk.</dd>
  %% </dl>
  %%
  %% @spec close(Db, Opts) -> ok | {error, Error}
  %% where
  