code: def create(cls, infile, config=None, params=None, mask=None):
          
  
          infile = os.path.abspath(infile)
          roi_file, roi_data = utils.load_data(infile)
  
          if config is None:
              config = roi_data['config']
              validate = False
          else:
              validate = True
  
          gta = cls(config, validate=validate)
          gta.setup(init_sources=False)
          gta.load_roi(infile, params=params, mask=mask)
          return gta
docs: Create a new instance of GTAnalysis from an analysis output file
          generated with `~fermipy.GTAnalysis.write_roi`.  By default
          the new instance will inherit the configuration of the saved
          analysis instance.  The configuration may be overriden by
          passing a configuration file path with the ``config``
          argument.
  
          Parameters
          ----------
  
          infile : str
              Path to the ROI results file.
  
          config : str
              Path to a configuration file.  This will override the
              configuration in the ROI results file.
  
          params : str
              Path to a yaml file with updated parameter values
          
          mask : str
              Path to a fits file with an updated mask