old_contents: /**
   * Module dependencies.
   */
  const Score     = require('./score');
  const mongoose  = require('mongoose');
  const Schema    = mongoose.Schema;
  
  // create a schema
  const gameSchema = new Schema({
    started_at: Date,
    ended_at: Date,
    teams: [Schema.Types.ObjectId],
    score: [Score.schema]
  });
  
  gameSchema.methods.start = function start(completion) {
    if (!this.started_at) {
      // game is already started
      this.started_at = new Date();
    }
  
  gameSchema.prototype.complete = function finishGame(completion) {
    if (ended_at) {
      // game is already completed
      return;
    }
  
    ended_at = new Date();
    completion();
  }
  
  // make this available to our users in our Node applications
  module.exports = Game;
  
new_contents: /**
   * Module dependencies.
   */
  const Score     = require('./score');
  const mongoose  = require('mongoose');
  const Schema    = mongoose.Schema;
  
  // create a schema
  const gameSchema = new Schema({
    started_at: Date,
    ended_at: Date,
    teams: [Schema.Types.ObjectId],
    score: [Score.schema]
  });
  
  gameSchema.methods.start = function start(completion) {
    if (!this.started_at) {
      // game is already started
      this.started_at = new Date();
    }
  
    completion();
  }
  
  gameSchema.methods.finish = function finish(completion) {
    if (!this.ended_at && this.started_at) {
      // game is already completed
      this.ended_at = new Date();
    }
  
    completion();
  }
  
  // make this available to our users in our Node applications
  module.exports = Game;
  
subject: Add finish function