serialization :: E :: semi_private
RestrictedSerializer.e.g. we want it on the DB but not in API/REST JSON messages
Note that the annotation noserialize hides the attribute for all serializers.
To hide the attribute only in the RestrictedSerializer, it will have to actively ignore it.
	# An attribute not to be serialized by the custom `RestrictedSerializer`.
	# e.g. we want it on the DB but not in API/REST JSON messages
	#
	# Note that the annotation `noserialize` hides the attribute for all serializers.
	# To hide the attribute only in the `RestrictedSerializer`, it will have to actively ignore it.
	var semi_private = "secret"
					lib/serialization/examples/custom_serialization.nit:58,2--63,28