Attempt to load an existing

def _get_existing_disposable_app(file, clientInfo, conf):
    """
    Attempt to load an existing 
    """
    if not os.path.isfile(file):
        return None
    else:
        data = None
        with open(file, 'r') as f:
            data = json.load(f)
        if not 'client' in data or not 'creds' in data:
            return None
        return _BlotreDisposableApp(file,
            data['client'],
            creds = data['creds'],
            config = conf)