code: def _adjust_bins(self, bins: int | np.ndarray | list[np.ndarray]):
      if is_integer(bins):
          if self.by is not None:
              by_modified = unpack_single_str_list(self.by)
              grouped = self.data.groupby(by_modified)[self.columns]
              bins = [
                  self._calculate_bins(group, bins)
                  for key, group in grouped
              ]
          else:
              bins = self._calculate_bins(self.data, bins)
      return bins
  
imports: from __future__ import annotations
  from typing import TYPE_CHECKING, Any, Literal, final
  import numpy
  from pandas.core.dtypes.common import is_integer, is_list_like
  from pandas.core.dtypes.generic import ABCDataFrame, ABCIndex
  from pandas.core.dtypes.missing import isna, remove_na_arraylike
  from pandas.io.formats.printing import pprint_thing
  from pandas.plotting._matplotlib.core import LinePlot, MPLPlot
  from pandas.plotting._matplotlib.groupby import create_iter_data_given_by, reformat_hist_y_given_by
  from pandas.plotting._matplotlib.misc import unpack_single_str_list
  from pandas.plotting._matplotlib.tools import create_subplots, flatten_axes, maybe_adjust_figure, set_ticks_props
label_desc: Use image node_id 3 for calling the HistPlot obj's underlying member method code with example usage: obj._adjust_bins(bins) and returns: bins