@classmethod
def isProxyValid(cls, proxy):
    """ checks if proxy is valid

        :param proxy: PyTango proxy
        :type proxy: :class:`PyTango.DeviceProxy`
        :returns: True if proxy is valid else false
        :rtype: :obj:`bool`

        """
    failed = True
    try:
        proxy.ping()
        failed = False
    except Exception:
        failed = True
    return not failed
