code: def GET_account_tokens(self, path_info, account_addr):
          
          if not check_account_address(account_addr):
              return self._reply_json({'error': 'Invalid address'}, status_code=400)
  
          blockstackd_url = get_blockstackd_url()
          res = blockstackd_client.get_account_tokens(account_addr, hostport=blockstackd_url)
          if json_is_error(res):
              log.error("Failed to load tokens for {}: {}".format(account_addr, res['error']))
              return self._reply_json({'error': 'Failed to load tokens for {}: {}'.format(account_addr, res['error'])}, status_code=res.get('http_status', 500))
  
          self._reply_json({'tokens': res})
          return
docs: Get all token types that an address owns
          Returns {'tokens': [...]}