def index(self, key):
        """
        Get the index of a given entry, raising an IndexError if it's not
        present.

        `key` can be an iterable of entries that is not a string, in which case
        this returns a list of indices.

        Example:
            >>> oset = OrderedSet([1, 2, 3])
            >>> oset.index(2)
            1
        """
        if is_iterable(key):
            return [self.index(subkey) for subkey in key]
        return self.map[key]

        Get the index of a given entry, raising an IndexError if it's not
        present.

        `key` can be an iterable of entries that is not a string, in which case
        this returns a list of indices.

        Example:
            >>> oset = OrderedSet([1, 2, 3])
            >>> oset.index(2)
            1
        
product/gradle-plugin/src/main/python/setuptools/_vendor/ordered_set.py