code: function parse(file) {
    var rules = {};
  
    file
      .split(/\n/m)
      .filter(function (line) {
        return (/^\/\//).test(line) ? null : line;
      })
      .map(function (line) {
        return process(line.split("."), rules);
      });
  
    return rules;
  }
docs: Parse domainname input file.
  http://mxr.mozilla.org/mozilla-central
  /source/netwerk/test/unit/data/test_psl.txt?raw=1
  
  @param  {String} file File content as string.
  @return {Object}      Parsed tree object.