code: def build_cols(cols, dtypes):
      """
      Helper function to add additional column entries for columns of type datetime so that users can make use of
      different frequencies of dates.  For example, hour, weekday, month, quarter, year
  
      :param cols: columns in dataframe
      :type cols: list of strings
      :param dtypes: datatypes of columns in dataframe
      :type dtypes: dict
      :return: generator or columns + any additional (datetime column + frequency) options
      """
      yield INDEX_COL, INDEX_COL
      for c in cols:
          if classify_type(dtypes[c]) == "D":
              for freq in FREQS:
                  if freq in FREQ_LABELS:
                      yield "{}{}{}".format(
                          c, CHART_JOINER_CHAR, freq
                      ), "{} ({})".format(c, FREQ_LABELS[freq])
                  else:
                      yield c, c
          else:
              yield c, c
  
file_path: dtale/dtale/dash_application/layout/utils.py
imports: import dash_bootstrap_components
  from dtale.dash_application import dcc, html
  from dtale.translations import text
  from dtale.utils import dict_merge, classify_type, flatten_lists, make_list
  from dtale.charts.utils import INDEX_COL
  from dtale.constants import CHART_JOINER_CHAR
label_desc: Use image node_id 4 for calling a global function with example usage: build_cols(cols, dtypes) without return types