title: Converting syntax diagram to ebnf
body: <p>I am a bit confused atm. </p>
  
  <p><img src="https://i.stack.imgur.com/5vacF.png" alt=""></p>
  
  <p>Should the ebnf form for this syntax graph be:</p>
  
  <p>Prog::= a|b</p>
  
  <p>Or</p>
  
  <p>Prog::= a[b]</p>