title: What does asynchronously recursive mean in nodejs
body: <p>In Mongoose documentation for validation they say "<strong>Validation is asynchronously recursive: when you call Model#save, sub-document validation is executed. If an error happens, your Model#save callback receives it</strong>" </p>
  
  <p>What do they mean by it? Suppose I have 5 validations than will they be run in parallel or series? Or is they get called in series with a callback that is received by the model save method?
  Please help me understand this? I know its a very easy question But I could not get any help from searching and all. So please.</p>