code: def is_valid_isbn(isbn):
      
      length = len(isbn)
  
      if length == 10:
          return is_isbn10_valid(isbn)
      elif length == 13:
          return is_isbn13_valid(isbn)
  
      return False
docs: Validate given `isbn`. Wrapper for :func:`is_isbn10_valid`/
      :func:`is_isbn13_valid`.
  
      Args:
          isbn (str/list): ISBN number as string or list of digits.
  
      Note:
          Function doesn't require `isbn` type to be specified (it can be both
          10/13 isbn's versions).
  
      Returns:
          bool: ``True`` if ISBN is valid.