def METHOD_NAME(
    self, batch: Sequence[RequestPrepare]
) -> Mapping[str, "CreateArtifactFilesResponseFile"]:
    """Execute the prepareFiles API call.
    Arguments:
        batch: List of RequestPrepare objects
    Returns:
        dict of (save_name: ResponseFile) pairs where ResponseFile is a dict with
            an uploadUrl key. The value of the uploadUrl key is None if the file
            already exists, or a url string if the file should be uploaded.
    """
    return self._api.create_artifact_files([req.file_spec for req in batch])