code: def get_knot_dates(start_date, knot_idx, freq):
      """
      Parameters
      ----------
      start_date : datetime array
      knot_idx : ndarray
          1D array containing index with `int` type.
      freq : date frequency
  
      Returns
      -------
      list :
          list of knot dates with provided start date time and indices
      """
      # knot_dates = knot_idx * freq + start_date
      # knot_dates = knot_idx * np.timedelta64(1, freq) + start_date
      dates_lst = pd.date_range(
          start=start_date, periods=max(knot_idx) + 1, freq=freq
      )
      knot_dates = dates_lst[knot_idx]
  
      return knot_dates
  
imports: import numpy
  import pandas
  from ..exceptions import IllegalArgument
label_desc: Use image node_id 1 for calling a global function with example usage: get_knot_dates(start_date, knot_idx, freq) and returns: knot_dates