title: dialog flow skipping a parameter based on another parameter
body: <p>I created an intent for my item selling store with name "Order". I want to ask user if he wants the item to be picked up or get delivered. </p>
  
  <p>if he is picking up then i do not need to capture his address. In my current implementation I created two required paramaters named "OrderType" and "deliveryAddress" </p>
  
  <p>so the question is how do i skip deliveryAddress capture if value of OrderType is pickup ? </p>
  
  <p>Please note that I am using fb messenger as a channel so the value of orderType would be coming from FB. </p>