def option(*param_decls, **attrs):
    """Attaches an option to the command.  All positional arguments are
    passed as parameter declarations to :class:`Option`; all keyword
    arguments are forwarded unchanged (except ``cls``).
    This is equivalent to creating an :class:`Option` instance manually
    and attaching it to the :attr:`Command.params` list.

    :param cls: the option class to instantiate.  This defaults to
                :class:`Option`.
    """
    def decorator(f):
        # Issue 926, copy attrs, so pre-defined options can re-use the same cls=
        option_attrs = attrs.copy()

        if 'help' in option_attrs:
            option_attrs['help'] = inspect.cleandoc(option_attrs['help'])
        OptionClass = option_attrs.pop('cls', Option)
        _param_memo(f, OptionClass(param_decls, **option_attrs))
        return f
    return decorator