code: function getSourceCodeOfFile(filename, options) {
      debug("getting sourceCode of", filename);
      const opts = Object.assign({}, options, { rules: {} });
      const cli = new CLIEngine(opts);
      const results = cli.executeOnFiles([filename]);
  
      if (results && results.results[0] && results.results[0].messages[0] && results.results[0].messages[0].fatal) {
          const msg = results.results[0].messages[0];
  
          throw new Error(`(${filename}:${msg.line}:${msg.column}) ${msg.message}`);
      }
      const sourceCode = cli.linter.getSourceCode();
  
      return sourceCode;
  }
docs: ------------------------------------------------------------------------------ Helpers ------------------------------------------------------------------------------ 
  Get the SourceCode object for a single file
  @param   {string}     filename The fully resolved filename to get SourceCode from.
  @param   {Object}     options  A CLIEngine options object.
  @returns {Array}               Array of the SourceCode object representing the file
  and fatal error message.