def check_missing_backends():
    """
    Checks if all backends are installed (otherwise the check of this script is incomplete). Will error in the CI if
    that's not the case but only throw a warning for users running this.
    """
    missing_backends = []
    if not is_torch_available():
        missing_backends.append("PyTorch")
    if not is_tf_available():
        missing_backends.append("TensorFlow")
    if not is_flax_available():
        missing_backends.append("Flax")
    if len(missing_backends) > 0:
        missing = ", ".join(missing_backends)
        if os.getenv("TRANSFORMERS_IS_CI", "").upper() in ENV_VARS_TRUE_VALUES:
            raise Exception(
                "Full repo consistency checks require all backends to be installed (with `pip install -e .[dev]` in the "
                f"Transformers repo, the following are missing: {missing}."
            )
        else:
            warnings.warn(
                "Full repo consistency checks require all backends to be installed (with `pip install -e .[dev]` in the "
                f"Transformers repo, the following are missing: {missing}. While it's probably fine as long as you "
                "didn't make any change in one of those backends modeling files, you should probably execute the "
                "command above to be on the safe side."
            )

    Checks if all backends are installed (otherwise the check of this script is incomplete). Will error in the CI if
    that's not the case but only throw a warning for users running this.
    
dpkd/transformers/utils/check_repo.py