code: def get_absolute_path(cls, roots, path):
          
          for root in roots:
              abspath = os.path.abspath(os.path.join(root, path))
              if abspath.startswith(root) and os.path.exists(abspath):
                  return abspath
          # XXX TODO
          return 'file-not-found'
docs: Returns the absolute location of ``path`` relative to one of
          the ``roots``.
  
          ``roots`` is the path configured for this `StaticFileHandler`
          (in most cases the ``static_path`` `Application` setting).