def bib_sublist(bibfile_data, val_type):
    """
    Sublist of bibfile_data whos elements are val_type

    This method examines each bib_dict element of a bibfile_data list and returns the subset which can be classified according to val_type.

    :param list bibfile_data: List containing `RefFile`s.
    :param type val_type:
    :rtype: list
    """
    sublist = [bibfile for bibfile in bibfile_data if isinstance(bibfile.bib, val_type)]
    return sublist