docs: def yeardec2datetime(atime: float) -> datetime.datetime:
      """
      Convert atime (a float) to DT.datetime
      This is the inverse of datetime2yeardec.
      assert dt2t(t2dt(atime)) == atime
  
      http://stackoverflow.com/questions/19305991/convert-fractional-years-to-a-real-date-in-python
      Authored by "unutbu" http://stackoverflow.com/users/190597/unutbu
  
      In Python, go from decimal year (YYYY.YYY) to datetime,
      and from datetime to decimal year.
      """
  # %%
      if isinstance(atime, (float, int)):  # typically a float
  
          year = int(atime)
          remainder = atime - year
          boy = datetime.datetime(year, 1, 1)
          eoy = datetime.datetime(year + 1, 1, 1)
          seconds = remainder * (eoy - boy).total_seconds()
  
          T = boy + datetime.timedelta(seconds=seconds)
          assert isinstance(T, datetime.datetime)
      elif isinstance(atime[0], float):
          return np.asarray([yeardec2datetime(t) for t in atime])
      else:
          raise TypeError('expecting float, not {}'.format(type(atime)))
  
      return T