title: How to reference another schema in my Mongoose schema?
body: <p>I'm building a Mongoose schema for a dating app. </p>
  
  <p>I want each <code>person</code> document to contain a reference to all the events they've been to, where <code>events</code> is another schema with its own models in the system. How can I describe this in the schema?</p>
  
  <pre><code>var personSchema = mongoose.Schema({
      firstname: String,
      lastname: String,
      email: String,
      gender: {type: String, enum: ["Male", "Female"]}
      dob: Date,
      city: String,
      interests: [interestsSchema],
      eventsAttended: ???
  });
  </code></pre>