input: Write a python function to scrape headlines from a given URL using BeautifulSoup.
  ```python
  assert scrape_headlines("https://example.com") == ['Example headline 1', 'Example headline 2']
  assert scrape_headlines("https://another-example.com") == ['Another headline 1', 'Another headline 2', 'Another headline 3']
output: def scrape_headlines(url):
      import requests
      from bs4 import BeautifulSoup
      
      response = requests.get(url)
      soup = BeautifulSoup(response.content, 'html.parser')
      headlines = []
      
      # Assuming headlines are in <h2> tags for this example
      for h2 in soup.find_all('h2'):
          headlines.append(h2.get_text())
      
      return headlines