docs: def download(url, filename=None):
  	"""
  	Download a file from a url and save it to disk.
  
  	:param str url: The URL to fetch the file from.
  	:param str filename: The destination file to write the data to.
  	"""
  	# requirements os, shutil, urllib.parse, urllib.request
  	if not filename:
  		url_parts = urllib.parse.urlparse(url)
  		filename = os.path.basename(url_parts.path)
  	url_h = urllib.request.urlopen(url)
  	with open(filename, 'wb') as file_h:
  		shutil.copyfileobj(url_h, file_h)
  	url_h.close()
  	return