code: def get_margin_balance(self, symbol):
          
          params = {}
          path = '/v1/margin/accounts/balance'
          if symbol:
              params['symbol'] = symbol
  
          def _wrapper(_func):
              @wraps(_func)
              def handle():
                  _func(api_key_get(params, path))
  
              return handle
  
          return _wrapper
docs: 借贷账户详情,支持查询单个币种
          :param symbol:
          :return: