function onWriteClbk( file ) {
	return onWrite;

	/**
	* Callback invoked after writing data to file.
	*
	* @private
	* @param {(Error|null)} error - error object
	*/
	function onWrite( error ) {
		if ( error ) {
			debug( 'Encountered an error when attempting to write data to file: %s', error.message );
			throw error;
		}
		debug( 'Successfully wrote data to file: %s', file );
		COUNT += 1;
		if ( COUNT === NUM_FILES ) {
			debug( 'Successfully converted all data files.' );
			debug( 'Reading directory contents: %s', dataDir );
			readDir( dataDir, onDir2 );
		}
	}
}
Returns a callback to be invoked after writing data to file.

@private
@param {string} file - file name
@returns {Callback} callback