All known File* classes

    Args:
        flag_leaf: returns only classes that do not have subclasses
                   ("leaf" nodes as in a class tree graph)

def classes_file(flag_leaf=False):
    """All known File* classes

    Args:
        flag_leaf: returns only classes that do not have subclasses
                   ("leaf" nodes as in a class tree graph)
    """
    if __flag_first:
        __setup()

    if not flag_leaf:
        return _classes_file

    return [cls for cls in _classes_file if cls not in _classes_file_superclass]