code: def from_stat_file(cls, statfile, timestep=1, is_leap_year=False):
          
          stat = STAT(statfile)
  
          # check to be sure the stat file does not have missing tau values
          def check_missing(opt_data, data_name):
              if opt_data == []:
                  raise ValueError('Stat file contains no optical data.')
              for i, x in enumerate(opt_data):
                  if x is None:
                      raise ValueError(
                          'Missing optical depth data for {} at month {}'.format(
                              data_name, i)
                      )
          check_missing(stat.monthly_tau_beam, 'monthly_tau_beam')
          check_missing(stat.monthly_tau_diffuse, 'monthly_tau_diffuse')
  
          return cls.from_ashrae_revised_clear_sky(stat.location, stat.monthly_tau_beam,
                                                   stat.monthly_tau_diffuse, timestep,
                                                   is_leap_year)
docs: Create an ASHRAE Revised Clear Sky wea object from the monthly sky
          optical depths in a .stat file.
  
          Args:
              statfile: Full path to the .stat file.
              timestep: An optional integer to set the number of time steps per
                  hour. Default is 1 for one value per hour.
              is_leap_year: A boolean to indicate if values are representing a leap year.
                  Default is False.