def _get_size(app_inst):
    """Helper method for getting the size of a backend object

    If app_inst is provided, we'll just parse the dict to get
    the size instead of making a separate http request
    """
    if 'data' in app_inst:
        app_inst = app_inst['data']
    sis = app_inst['storage_instances']
    found_si = sis[0]
    found_vol = found_si['volumes'][0]
    return found_vol['size']
