How to use the wechatpy.utils.json.loads function in wechatpy

def wechat_api_mock(url, request):
    path = url.path.replace('/cgi-bin/', '').replace('/', '_')
    if path.startswith('_'):
        path = path[1:]
    res_file = os.path.join(_FIXTURE_PATH, '%s.json' % path)
    content = {
        'errcode': 99999,
        'errmsg': 'can not find fixture %s' % res_file,
    }
    headers = {
        'Content-Type': 'application/json'
    }
    try:
        with open(res_file, 'rb') as f:
            content = json.loads(f.read().decode('utf-8'))
    except (IOError, ValueError) as e:
        content['errmsg'] = 'Loads fixture {0} failed, error: {1}'.format(
            res_file,
            e
        )
    return response(200, content, headers, request=request)

def wechat_api_mock(url, request):
    path = url.path.replace('/cgi-bin/', '').replace('/', '_')
    if path.startswith('_'):
        path = path[1:]
    res_file = os.path.join(_FIXTURE_PATH, '%s.json' % path)
    content = {
        'errcode': 99999,
        'errmsg': 'can not find fixture %s' % res_file,
    }
    headers = {
        'Content-Type': 'application/json'
    }
    try:
        with open(res_file, 'rb') as f:
            content = json.loads(f.read().decode('utf-8'))
    except (IOError, ValueError) as e:
        print(e)
    return response(200, content, headers, request=request)

def _decode_result(self, res):
        try:
            result = json.loads(res.content.decode('utf-8', 'ignore'), strict=False)
        except (TypeError, ValueError):
            # Return origin response object if we can not decode it as JSON
            logger.debug('Can not decode response as JSON', exc_info=True)
            return res
        return result

def get(self, key, default=None):
        try:
            with open('%s-%s'%(self.file_dir, key), 'r') as f:
                _dict = json.loads(to_text(f.read()))
                timestamp = time.time()
                expires_at = _dict.get('expires_at', 0)
                if expires_at==0 or expires_at - timestamp > 60:
                    return _dict['val']
        except:
            traceback.print_exc()
            return default