'Determine if the storage system\'s password status is valid.
The password status has the following possible states: unknown, valid,
invalid.
If the password state cannot be retrieved from the storage system,
an empty string will be returned as the status, and the password
status will be assumed to be valid. This is done to ensure that
access to a storage system will not be blocked in the event of a
problem with the API.
This method returns a tuple consisting of the storage system\'s
password status and whether or not the status is valid.
Example: (invalid, True)
:returns: (str, bool)'

def _check_password_status(self, system):

    status = system.get('passwordStatus')
    status = (status.lower() if status else '')
    return (status, (status not in ['invalid', 'unknown']))
