Reset slots during form validation

[ChrisRahme (Chris Rahmé)]

First, you use the format {slot: value} in slot validation and [SlotSet(slot, value)] in run().

If you want to unset a slot in run(), use None with SlotSet():

if flag == 1:
    return [SlotSet("pizza_type", None), SlotSet("pizza_quantity", None)]
else:
    return [SlotSet("pizza_type", slot_pizza_type)]

If you want to unset a slot in validation, use a dictionary:

if flag == 1:
    return {"pizza_type": None, "pizza_quantity": None}
else:
    return {"pizza_type": slot_pizza_type}