Check that the index 'index' lies within the set of indexes.
    :param index: Index to determine whether it falls within the range or index pairs.
    :param index_ranges: A list of index pairs, monotonically increasing pairs.
    :return: True if the given index lies within a range specified by an index pair, False otherwise.

def _check_index_within_index_pairs(index, index_ranges):
    """
    Check that the index 'index' lies within the set of indexes.
    :param index: Index to determine whether it falls within the range or index pairs.
    :param index_ranges: A list of index pairs, monotonically increasing pairs.
    :return: True if the given index lies within a range specified by an index pair, False otherwise.
    """
    in_range = False
    for index_range in index_ranges:
        if index_range[0] < index < index_range[1]:
            in_range = True
    return in_range