code: func (t *Transaction) DeleteAll(c *Collection, count *int) {
  	if c == nil {
  		t.setError(newNilCollectionError("DeleteAll"))
  		return
  	}
  	if !c.index {
  		t.setError(newUnindexedCollectionError("DeleteAll"))
  		return
  	}
  	var handler ReplyHandler
  	if count == nil {
  		handler = nil
  	} else {
  		handler = NewScanIntHandler(count)
  	}
  	t.DeleteModelsBySetIDs(c.IndexKey(), c.Name(), handler)
  }
docs: // DeleteAll delets all models for the given model type in an existing transaction.
  // The value of count will be set to the number of models that were successfully deleted
  // when the transaction is executed. Any errors encountered will be added to the transaction
  // and returned as an error when the transaction is executed. You may pass in nil
  // for count if you do not care about the number of models that were deleted.