def arch(session):
    """
    Description: return windows architecture

    :param session: instance of Windows, which hold session to win machine
    :type session: winremote.Windows
    :returns: windows architecture (32-bit, 64-bit, ...)
    :rtype: str
    """
    return session._wmi.query_first(
        'select OSArchitecture from Win32_OperatingSystem')['OSArchitecture']
