example: https://github.com/onnx/onnx/blob/main/onnx/subbyte.py

"@typing_extensions.deprecated(
"Deprecated since 1.18. Scheduled to remove in 1.20. Consider using libraries like ml_dtypes for dtype conversion",
category=DeprecationWarning,
)
def float32_to_4bit_unpacked(x: np.ndarray | float, signed: bool) -> np.ndarray:
"""Cast to 4bit"

=> @justinchuby Should we remove it? Or would you like to wait a little longer?