input: Write a python function to scrape city data from a given URL and return a list of tuples containing city name, country, population, and area.
  assert scrape_city_data('http://example.com/cities') == [('City1', 'Country1', '1000000', '2000'), ('City2', 'Country2', '500000', '1500')]
  assert scrape_city_data('http://example.com/another_cities') == [('CityA', 'CountryA', '200000', '500'), ('CityB', 'CountryB', '300000', '700')]
  assert scrape_city_data('http://example.com/yet_another_cities') == [('CityX', 'CountryX', '700000', '1200'), ('CityY', 'CountryY', '400000', '900')]
output: import requests
  from bs4 import BeautifulSoup
  
  def scrape_city_data(url):
      response = requests.get(url)
      soup = BeautifulSoup(response.content, 'html.parser')
      cities = []
  
      for city in soup.find_all('city'):
          name = city.find('name').text
          country = city.find('country').text
          population = city.find('population').text
          area = city.find('area').text
          cities.append((name, country, population, area))
  
      return cities