input: Write a function to determine if it is possible to create a HTML page that displays a table of contents from the data stored in a database. If it is possible return True else return False. If the input is empty then return True.
  assert display_table_of_contents([{'section': 'Introduction', 'page': 1}, {'section': 'Methods', 'page': 2}, {'section': 'Conclusion', 'page': 3}])==True
  assert display_table_of_contents([])==True
  assert display_table_of_contents([{'section': 'Random', 'page': 'invalid'}, {'section': 'Data', 'page': 'error'}])==False
  assert display_table_of_contents([{'section': 'Tech', 'page': 4}, {'section': 'Science', 'page': 'undefined'}])==False
output: def display_table_of_contents(data):
      if not data:
          return True
      for item in data:
          if not isinstance(item['page'], int):
              return False
      return True