lib/Model.js
function (model, schema) {
  debug('applying virtuals');
  for (const i in schema.virtuals) {
    schema.virtuals[i].applyVirtuals(model);
  }
}
function (model, schema) {
  debug('applying virtuals');
  for (const i in schema.virtuals) {
    schema.virtuals[i].applyVirtuals(model);
  }
}
/*!
Register virtuals for this model
@param {Model} model
@param {Schema} schema