text: function variableNames(text) {
      let result = [];
      let pattern = /\b_([A-Za-z0-9]+)\b/g;
      let matches = pattern.exec(text);
  
      while(matches){
          result.push(matches[1]);
          matches = pattern.exec(text);
      }
      
      console.log(result.join(','));
  }
  
  variableNames('The _id and _age variables are both integers.');