def check_keys(*keys: str) -> None:
    """
    Check that all keys named in `*args` are set as env vars. Will fail with a
    message on how to set missing key if one is missing. If all are provided
    somewhere, they will be set in the env var as the canonical location where
    we should expect them subsequently.

    Example:
        ```python
        from trulens.core.utils.keys import check_keys

        check_keys(
            "OPENAI_API_KEY",
            "HUGGINGFACE_API_KEY"
        )
        ```
    """

    kvals = _collect_keys(*keys)
    missing_keys = []
    for k in keys:
        v = kvals.get(k)
        _check_key(k, v=v)
        if v is not None:
            # Put value in redaction list.
            values_to_redact.add(v)
            os.environ[k] = v
        else:
            missing_keys.append(k)
    if missing_keys:
        raise MissingKeyError(missing_keys=missing_keys)

    Check that all keys named in `*args` are set as env vars. Will fail with a
    message on how to set missing key if one is missing. If all are provided
    somewhere, they will be set in the env var as the canonical location where
    we should expect them subsequently.

    Example:
        ```python
        from trulens.core.utils.keys import check_keys

        check_keys(
            "OPENAI_API_KEY",
            "HUGGINGFACE_API_KEY"
        )
        ```
    
src/core/trulens/core/utils/keys.py