How to get value of one virtual field from another?

Question

I have two virtual fields. For example, A and B. I want to get the value of A from B. I tried to access the value using this but it returns undefined.

I have simplified my code here.

exampleSchema.virtual('A').get(function () {
  return this.example ? true : false; // suppose I have a field called example in my document
});

exampleSchema.virtual('B').get(function () {
  return this.A ? false : true; // this.A doesn't work. It returns undefined
});

Any help would be appreciated. Thanks in advance.