ShaderGraph CodeFunctionNode inaccessible due to it's protection level.

I added the shader graph package to my project then added a custom node script but it says the base class CodeFunctionNode is inaccessible due to it’s protection level. From everything I can find online this is the way to create custom nodes so why is it inaccessible? Is there a fix for this?

Looks like this feature is being deprecated in favor of the new Custom Function node. See this forum post: