input: Write a python function to fetch the last page number of a given PTT board.
  assert get_last_page("Gossiping") > 0
  assert isinstance(get_last_page("Tech_Job"), int)
  assert get_last_page("NBA") >= 1
output: def get_last_page(board):
      import requests
      from bs4 import BeautifulSoup
      
      url = f"https://www.ptt.cc/bbs/{board}/index.html"
      response = requests.get(url)
      soup = BeautifulSoup(response.text, 'html.parser')
      pagination = soup.select('.btn.wide')
      
      if len(pagination) < 2:
          return 1
      
      last_page_url = pagination[-2]['href']
      last_page_num = int(last_page_url.split('index')[1].split('.html')[0]) + 1
      
      return last_page_num