keras/src/ops/linalg.py/Norm/__init__
class Norm:    def __init__(self, ord=None, axis=None, keepdims=False):
        super().__init__()
        if isinstance(ord, str):
            if ord not in ("fro", "nuc"):
                raise ValueError(
                    "Invalid `ord` argument. "
                    "Expected one of {'fro', 'nuc'} when using string. "
                    f"Received: ord={ord}"
                )
        if isinstance(axis, int):
            axis = [axis]
        self.ord = ord
        self.axis = axis
        self.keepdims = keepdims