input: def extract_web_data(url: str, tag: str, attribute: str) -> List[str]:
      """Creates a web scraper that uses BeautifulSoup to parse webpages and extract specific data. It extracts the specified attribute from the elements with the provided tag and returns the extracted data.
      
      >>> extract_web_data("https://example.com", 'a', 'href')
      ['https://example.com/page1', 'https://example.com/page2']
      >>> extract_web_data("https://example.com", 'h1', 'class')
      ['main-header', 'secondary-header']
      """
      import requests
      from bs4 import BeautifulSoup
  
      # Get the web page
      webpage = requests.get(url)
  
      # Parse the web page
      soup = BeautifulSoup(webpage.content, 'html.parser')
  
      # Find all elements with the specified tag
      elements = soup.find_all(tag)
  
      # Extract the specified attribute from the elements
      extracted_data = [element.get(attribute) for element in elements]
  
      return extracted_data
output:     # Filter out None values
      extracted_data = [data for data in extracted_data if data is not None]
  
      return extracted_data