code: def infer_timedelta_units(deltas):
      
      deltas = pd.to_timedelta(np.asarray(deltas).ravel(), box=False)
      unique_timedeltas = np.unique(deltas[pd.notnull(deltas)])
      units = _infer_time_units_from_diff(unique_timedeltas)
      return units
docs: Given an array of timedeltas, returns a CF compatible time-unit from
      {'days', 'hours', 'minutes' 'seconds'} (the first one that can evenly
      divide all unique time deltas in `deltas`)