input: Write a python function to extract the values of all "option" tags within a given HTML string.
  ```python
  def extract_option_values(html):
      # Your code here
  
  assert extract_option_values('<select><option value="c">C</option><option value="java">Java</option><option value="python">Python</option></select>') == ["c", "java", "python"]
  assert extract_option_values('<select><option value="1">One</option><option value="2">Two</option></select>') == ["1", "2"]
  assert extract_option_values('<select></select>') == []
output: def extract_option_values(html):
      from bs4 import BeautifulSoup
      soup = BeautifulSoup(html, 'html.parser')
      return [option['value'] for option in soup.find_all('option')]