operator_convert extending primitives

Is it possible to add operator_convert to primitives.

For example I have a nullable string class that inherits from nullablePrimitive. I added an operator_convert method so that it can automatically be passed to methods that accept strings, but now I want the opposite to be true. I want you to be able to pass a string to a method that is expecting the NullableString class and have it use the operator_convert to change the string automatically into the NullableString class. Is this possible?

Apparently my issue was using a return type. I needed to remove the return type and use “self” to set up the value