input: Write a function to create a web scraper using Python's Selenium that retrieves product names from an online store. The function should initialize a Firefox session, navigate to the store's homepage, perform a search for "shoes", and print the names of all products displayed in the search results. Finally, the function should close the browser window.
  assert web_scraper().strip() == "Expected product names from search results"
output: def web_scraper():
      from selenium import webdriver
      from selenium.webdriver.common.by import By
      from selenium.webdriver.common.keys import Keys
      import time
  
      driver = webdriver.Firefox()
      driver.get("https://example-store.com")
      
      search_box = driver.find_element(By.NAME, "q")
      search_box.send_keys("shoes")
      search_box.send_keys(Keys.RETURN)
      
      time.sleep(5)  # Wait for the search results to load
      
      product_names = driver.find_elements(By.CLASS_NAME, "product-name")
      result = "\n".join([name.text for name in product_names])
      
      driver.quit()
      
      return result