class_docstr: Base class for all objects stored in Bokeh |Document| instances.
  
      
class_docstr_tok: ["Base","class","for","all","objects","stored","in","Bokeh","|Document|","instances","."]
docstr: Add a callback on this object to trigger when ``attr`` changes.
  
  Args:
      attr (str) : an attribute name on this object
      *callbacks (callable) : callback functions to register
  
  Returns:
      None
  
  Examples:
  
      .. code-block:: python
  
          widget.on_change('value', callback1, callback2, ..., callback_n)
code: def on_change(self, attr: str, *callbacks: PropertyCallback) -> None:
      """Add a callback on this object to trigger when ``attr`` changes.
  
      Args:
          attr (str) : an attribute name on this object
          *callbacks (callable) : callback functions to register
  
      Returns:
          None
  
      Examples:
  
          .. code-block:: python
  
              widget.on_change('value', callback1, callback2, ..., callback_n)
  
      """
      descriptor = self.lookup(attr)
      super().on_change(descriptor.name, *callbacks)
  
imports: from __future__ import annotations
  import logging
  from inspect import Parameter, Signature, isclass
  from typing import TYPE_CHECKING, Any, Iterable
  from ..core import properties
  from ..core.has_props import HasProps, _default_resolver, abstract
  from ..core.property._sphinx import type_link
  from ..core.property.validation import without_property_validation
  from ..core.serialization import ObjectRefRep, Ref, Serializer
  from ..core.types import ID
  from ..events import Event
  from ..themes import default
  from ..util.callback_manager import EventCallbackManager, PropertyCallbackManager
  from ..util.serialization import make_id
  from .docs import html_repr, process_example
  from .util import HasDocumentRef, collect_models, visit_value_and_its_immediate_references
label_desc: Use image node_id 12 for calling the Model obj's underlying member method code with example usage: obj.on_change(attr) without return types