code: def dynamize_attribute_updates(self, pending_updates):
          
          d = {}
          for attr_name in pending_updates:
              action, value = pending_updates[attr_name]
              if value is None:
                  # DELETE without an attribute value
                  d[attr_name] = {"Action": action}
              else:
                  d[attr_name] = {"Action": action,
                                  "Value": self.dynamize_value(value)}
          return d
docs: Convert a set of pending item updates into the structure
          required by Layer1.