def values(min=None, max=None, excludemin=False, excludemax=False, doc_id=None
    ):
    """return an iterables of the values in the index.

        if doc_id is provided, returns the values only for that document id.

        If a min is specified, then output is constrained to values greater
        than or equal to the given min, and, if excludemin is specified and
        true, is further constrained to values strictly greater than min.  A
        min value of None is ignored.  If min is None or not specified, and
        excludemin is true, the smallest value is excluded.

        If a max is specified, then output is constrained to values less than
        or equal to the given max, and, if excludemax is specified and
        true, is further constrained to values strictly less than max.  A max
        value of None is ignored.  If max is None or not specified, and
        excludemax is true, the largest value is excluded.
        """
