code: def test_add(portfolio, exchange):
      wallet_bch = Wallet(exchange, 1000 * BCH)
  
      portfolio.add(wallet_bch)
  
      assert wallet_bch in portfolio.wallets
  
imports: import pytest
  import unittest.mock
  from tensortrade.core.base import Clock
  from tensortrade.oms.wallets import Wallet, Portfolio
  from tensortrade.oms.instruments import USD, BTC, ETH, XRP, BCH
label_desc: Use image node_id 18 for calling a global function with example usage: test_add(portfolio, exchange) without return types