keras/src/layers/core/einsum_dense.py/EinsumDense/_quantization_mode_error
class EinsumDense:    def _quantization_mode_error(self, mode):
        return NotImplementedError(
            "Invalid quantization mode. Expected one of "
            f"{dtype_policies.QUANTIZATION_MODES}. "
            f"Received: quantization_mode={mode}"
        )