def download_webfile(url, filename, overwrite=False):
 if (os.path.exists(filename) and (not overwrite)):
  return
 if ('.' in url):
  urlretrieve(url, filename)
 else:
  try:
   subprocess_call(['youtube-dl', url, '-o', filename])
  except OSError as e:
   raise OSError((e.message + '\n A possible reason is that youtube-dl is not installed on your computer. Install it with  "pip install youtube-dl"'))

def download_webfile ( url , filename , overwrite = False ) : if ( os . path . exists ( filename ) and ( not overwrite ) ) : return if ( '.' in url ) : urlretrieve ( url , filename ) else : try : subprocess_call ( [ 'youtube-dl' , url , '-o' , filename ] ) except OSError as e : raise OSError ( ( e . message + '\n A possible reason is that youtube-dl is not installed on your computer. Install it with  "pip install youtube-dl"' ) )
small utility to download the file at url under name filename .