How to remove un used object literal using `ts-morph`?

Question

I have a language file which exports the texts as object literal,

export const lang = {
    hello : `hello`, 
    calculate : (value = 0) => `the value is ${value}`,
    nested: {
         value: 'nested value'
    }
}

This constant is imported by many different files in the project. I am trying to find the properties that are un used and remove them.

  const project = new Project({ tsConfigFilePath: 'tsconfig.webpack.json' });
  const source = project.addSourceFileAtPathIfExists('constants.ts');
  const messages = source?.getVariableDeclarationOrThrow('lang');
  const value = messages?.getInitializerOrThrow();
  const properties = (value as ObjectLiteralExpression)?.getProperties() ?? [];
  
  // I can iterate each property and their child but how to check if they are unused?? 

Is there any way to know that a property is un used and remove it?