code: def default_star(cls, starA='starA', force_build=False):
          
          if not force_build and not conf.devel:
              b = cls.open(os.path.join(_bundle_cache_dir, 'default_star.bundle'))
  
              if starA != 'starA':
                  b.rename_component('starA', starA)
  
              return b
  
          b = cls()
          # IMPORTANT NOTE: if changing any of the defaults for a new release,
          # make sure to update the cached files (see frontend/default_bundles
          # directory for script to update all cached bundles)
          b.add_star(component=starA)
          b.set_hierarchy(_hierarchy.component(b[starA]))
          b.add_compute(distortion_method='rotstar', irrad_method='none')
          return b
docs: For convenience, this function is available at the top-level as
          <phoebe.default_star> as well as <phoebe.frontend.bundle.Bundle.default_star>.
  
          sun
  
          This is a constructor, so should be called as:
  
          >>> b = Bundle.default_binary()
  
          Arguments
          -----------
          * `starA` (string, optional, default='starA'): the label to be set for
              starA.
          * `force_build` (bool, optional, default=False): whether to force building
              the bundle from scratch.  If False, pre-cached files will be loaded
              whenever possible to save time.
  
          Returns
          -----------
          * an instantiated <phoebe.frontend.bundle.Bundle> object.