text: const mongoose = require('mongoose');
  const { Schema } = mongoose;
  const { RequiredString } = require('../util/mongoose-helpers');
  
  const schema = new Schema({
  
      content: RequiredString,
      author: {
          type: Schema.Types.ObjectId,
          ref: 'User'
      },
      question: {
          type: Schema.Types.ObjectId,
          ref: 'Question',
          required: true
      }
  });
  
  module.exports = mongoose.model('Answer', schema);