input: Write a function to create a web scraper that extracts specific data from a given website. The function should utilize the Python package BeautifulSoup to parse webpages and extract the required data. The web scraper should allow finding HTML elements on the webpage using tags and attributes, converting the data into the desired format, and storing the extracted data.
  assert scraper("<url_of_webpage>")==["<url1>", "<url2>"]
  assert scraper("<url_of_webpage>")==["<url3>", "<url4>"]
output: def scraper(url):
      import requests
      from bs4 import BeautifulSoup
      response = requests.get(url)
      soup = BeautifulSoup(response.text, 'html.parser')
      links = soup.find_all('a', href=True)
      urls = [link['href'] for link in links]
      return urls