code: def aggregate(self, func, *args, **kwargs):
      raise NotImplementedError("aggregate is not implemented.")
  
imports: from __future__ import annotations
  import datetime
  from functools import partial
  from textwrap import dedent
  from typing import TYPE_CHECKING
  import numpy
  from pandas._libs.tslibs import Timedelta
  import pandas._libs.window.aggregations
  from pandas._typing import Axis, TimedeltaConvertibleTypes
  from pandas.util._decorators import doc
  from pandas.core.dtypes.common import is_datetime64_ns_dtype, is_numeric_dtype
  from pandas.core.dtypes.missing import isna
  from pandas.core import common
  from pandas.core.indexers.objects import BaseIndexer, ExponentialMovingWindowIndexer, GroupbyIndexer
  from pandas.core.util.numba_ import get_jit_arguments, maybe_use_numba
  from pandas.core.window.common import zsqrt
  from pandas.core.window.doc import _shared_docs, create_section_header, kwargs_numeric_only, numba_notes, template_header, template_returns, template_see_also, window_agg_numba_parameters
  from pandas.core.window.numba_ import generate_numba_ewm_func, generate_numba_ewm_table_func
  from pandas.core.window.online import EWMMeanState, generate_online_numba_ewma_func
  from pandas.core.window.rolling import BaseWindow, BaseWindowGroupby
label_desc: Use image node_id 3 for calling the OnlineExponentialMovingWindow obj's underlying member method code with example usage: obj.aggregate(func) without return types