old_contents: Posts = new Mongo.Collection('posts');
  
  Meteor.methods({
    postInsert: function(postAttributes) {
      check(Meteor.userId(), String);
      check(postAttributes, {
        title: String,
        url: String
      });
      var user = Meteor.user();
      var post = _.extend(postAttributes, {
        userId: user._id, 
        author: user.username, 
        submitted: new Date()
      });
      var postId = Posts.insert(post);
      return {
        _id: postId
      };
    }
  });
new_contents: Posts = new Mongo.Collection('posts');
  
  Meteor.methods({
    postInsert: function(postAttributes) {
      check(Meteor.userId(), String);
      check(postAttributes, {
        title: String,
        url: String
      });
  
      var postWithSameLink = Posts.findOne({url: postAttributes.url});
      if (postWithSameLink) {
        return {
          postExists: true,
          _id: postWithSameLink._id
        }
      }
  
      var user = Meteor.user();
      var post = _.extend(postAttributes, {
        userId: user._id, 
        author: user.username, 
        submitted: new Date()
      });
  
      var postId = Posts.insert(post);
      return {
        _id: postId
      };
      
    }
  });
subject: Check URL for duplicates