def resource_file_format(value):
    """Space-separated resource references in filename=blobsource format."""
    try:
        file_name, blob_source = value.split('=', 1)
    except ValueError:
        message = (
            'Incorrectly formatted resource reference. Argument values should be in the format filename=blobsource'
            )
        raise ValueError(message)
    return {'file_path': file_name, 'blob_source': blob_source}
