code: def __call__(self, event):
      self.event_name = event.event_name
      self.payload = {
          attr: getattr(event, attr) for attr in self.attributes
      }
  
imports: from __future__ import annotations
  import pytest
  from bokeh.core.serialization import Deserializer
  from bokeh.models import Button, Div, Plot, TextInput
  from bokeh import events
label_desc: Use image node_id 2 for calling the EventCallback obj's underlying member method code with example usage: obj.__call__(event) without return types