title: asp.net core 2.0 app.Run call twice?
body: <p>when i create new project empty in asp.net core 2.0, and write some code. And debug, but i see app.Run run twice once when i refresh in browser, but i don't understand why? somebody help me
  see this code in program.cs
  <a href="https://i.stack.imgur.com/Nrq9k.png" rel="nofollow noreferrer">code in program.cs</a></p>
  
  <p>and see this code in startup.cs
  <a href="https://i.stack.imgur.com/UHhwU.png" rel="nofollow noreferrer">code in startup.cs</a></p>
  
  <p>i don't understand i is always even(0,2,4,6,8....n), but i debug code, i can old (1,3,5,7.....), and app.Run call to twice. why? help me understand it.</p>