old_contents: import sublime, sublime_plugin
  
  class SetSyntaxForBuck(sublime_plugin.EventListener):
      def on_activated(self, view):
          if view.file_name().endswith("BUCK"):
              view.set_syntax_file("Packages/Python/Python.tmLanguage")
  
new_contents: import sublime, sublime_plugin
  
  class SetSyntaxForBuck(sublime_plugin.EventListener):
      def on_activated(self, view):
          if view.file_name() is not None and view.file_name().endswith("BUCK"):
              view.set_syntax_file("Packages/Python/Python.tmLanguage")
  
subject: Fix BUCK highlight (again)