def get_parent_comment(child_map, parent_id):
    """Get the parent comment's OrderedDict.

    :param OrderedDict child_map: The parent-child relationship mapping.
    :param str parent_id: The parent comment's ID.

    :returns: The parent comment's mapping.
    :rtype: OrderedDict
    """

    for child in child_map.values():
        if child[0] == parent_id:
            return child[1]
        parent = get_parent_comment(child[1], parent_id)
        if parent is not None:
            return parent