input: Write a python function to extract product prices from a given URL using requests and BeautifulSoup libraries.
  assert extract_prices('https://example.com/store') == ['$19.99', '$29.99', '$39.99']
  assert extract_prices('https://example.com/anotherstore') == ['$9.99', '$14.99', '$24.99']
output: def extract_prices(url):
      import requests
      from bs4 import BeautifulSoup
      
      response = requests.get(url)
      soup = BeautifulSoup(response.content, 'html.parser')
      
      prices = []
      for price_tag in soup.find_all(class_='price'):
          prices.append(price_tag.get_text())
      
      return prices