How is Flask-Login's request_loader related to user_loader?
<p>I apologize in advance for asking a rather cryptic question.  However, I did not understand it despite going through a lot of material. It would be great if you could shed some light on this.</p>

<p>What is the purpose of a request_loader in flask-login?  How does it interact with the user_loader decorator?  </p>

<p>If I am using a token based authentication system (I am planning on sending the token to my angularJS front end, storing the token there and sending that token in the authorization-token header), will I need a request_loader or will a user_loader (where I check the auth header and see if the user exists) suffice?</p>