keras/src/dtype_policies/dtype_policy_map.py/DTypePolicyMap/from_config
class DTypePolicyMap:    def from_config(cls, config, custom_objects=None):
        from keras.src.saving import serialization_lib

        config = config.copy()
        config["policy_map"] = serialization_lib.deserialize_keras_object(
            config["policy_map"], custom_objects=custom_objects
        )
        return cls(**config)