input: Write a python function to add buttons to a menu and render it as HTML.
  assert isinstance(menu._render_menu(), str)
  assert '<a href="javascript:action1">Button 1</a>' in menu._render_menu()
  assert '<a href="javascript:action2">Button 2</a>' in menu._render_menu()
output: class Menu:
      def __init__(self):
          self.buttons = []
  
      def add_button(self, name, action):
          self.buttons.append((name, action))
  
      def _render_menu(self):
          return ''.join(f'<a href="javascript:{action}">{name}</a>' for name, action in self.buttons)
  
  # Usage example
  menu = Menu()
  menu.add_button('Button 1', 'action1')
  menu.add_button('Button 2', 'action2')