input: Write a python function to extract product names and prices from an HTML page using BeautifulSoup.
  assert extract_product_info('<div class="product"><span class="name">Product1</span><span class="price">$10</span></div>') == [('Product1', '$10')]
  assert extract_product_info('<div class="product"><span class="name">Product1</span><span class="price">$10</span></div><div class="product"><span class="name">Product2</span><span class="price">$20</span></div>') == [('Product1', '$10'), ('Product2', '$20')]
  assert extract_product_info('<div class="product"><span class="name">Product1</span><span class="price">$10</span></div><div class="product"><span class="name">Product2</span><span class="price">$20</span></div><div class="product"><span class="name">Product3</span><span class="price">$30</span></div>') == [('Product1', '$10'), ('Product2', '$20'), ('Product3', '$30')]
output: def extract_product_info(html):
      from bs4 import BeautifulSoup
      soup = BeautifulSoup(html, 'html.parser')
      products = []
      for product in soup.find_all('div', class_='product'):
          name = product.find('span', class_='name').text
          price = product.find('span', class_='price').text
          products.append((name, price))
      return products