code: function cached(grammar_file) {
    var fs      = require('fs'),
        path    = require('path'),
        change  = fs.statSync(grammar_file).mtime.valueOf(),
        cache   = [cache_path,'/', path.basename(grammar_file), '.', change, '.js'].join('');
  
    if(!fs.existsSync(cache_path))
      fs.mkdirSync(cache_path);
  
    if(fs.existsSync(cache))
      return fs.readFileSync(cache, 'utf8');
  
    var result = load(grammar_file);
    fs.writeFileSync(cache, result);
    return result;
  }
docs: Internal function to cache grammars. Creates a `.cache` directory in the current
  working path.