code: def since(version):
      
      import re
      indent_p = re.compile(r'\n( +)')
  
      def deco(f):
          indents = indent_p.findall(f.__doc__)
          indent = ' ' * (min(len(m) for m in indents) if indents else 0)
          f.__doc__ = f.__doc__.rstrip() + "\n\n%s.. versionadded:: %s" % (indent, version)
          return f
      return deco
docs: A decorator that annotates a function to append the version of Spark the function was added.