code: def safe_str_to_class(s):
      
      lst = s.split(".")
      klass = lst[-1]
      mod_list = lst[:-1]
      module = ".".join(mod_list)
  
      # ruby compatibility kludge: resque sends just a class name and
      # not a module name so if I use resque to queue a ruby class
      # called "Worker" then pyres will throw a "ValueError: Empty
      # module name" exception.  To avoid that, if there's no module in
      # the json then we'll use the classname as a module name.
      if not module:
          module = klass
  
      mod = my_import(module)
      if hasattr(mod, klass):
          return getattr(mod, klass)
      else:
          raise ImportError('')
docs: Helper function to map string class names to module classes.