code: def test_remove_pair(portfolio, exchange):
      portfolio.remove_pair(exchange, BTC)
  
      assert wallet_btc not 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 20 for calling a global function with example usage: test_remove_pair(portfolio, exchange) without return types