code: function RuleSet(filename) {
                //this.rules = [];
                this.rules = {};
  
                if (filename) {
                  // Read transformation rules
                  try {
                    var data = fs.readFileSync(filename, 'utf8');
                    this.rules = TF_Parser.parse(data);
                    // console.log(this.rules);
                    // console.log('Brill_POS_Tagger.read_transformation_rules: number of transformation rules read: ' + this.rules.length);
                  }
                  catch (error) {
                    console.error(error);
                  }
                }
              }
docs: /*
  Set of transformation rules
  Copyright (C) 2017 Hugo W.L. ter Doest
  
  This program is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.
  
  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
  
  You should have received a copy of the GNU General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.