code: function load( filename ){
  
    // path not specified / file does not exist
    try {
      if( !fs.lstatSync(filename).isFile() ){
        throw new Error( 'invalid file' );
      }
    } catch(e){
      throw new Error( 'file not found' );
    }
  
    // parse solr synonyms format
    return parse( fs.readFileSync( filename, 'utf8' ) );
  }
docs: https://www.elastic.co/guide/en/elasticsearch/reference/2.4/analysis-synonym-tokenfilter.html