text: const mongoose = require('mongoose');
  const { Schema } = mongoose;
  const HistoryEntry = require('./HistoryEntry');
  
  const accountSchema = new Schema({
    number: String,
    user: { type: Schema.Types.ObjectId, ref: 'users' },
    balance: { type: Number, default: 0 },
    contacts: [{ type: Schema.Types.ObjectId, ref: 'users' }],
    history: [HistoryEntry]
  });
  
  mongoose.model('accounts', accountSchema);
  