def get_lus2frames(framenet):
    """
    Returns a mapping of Lexical Units to sets of Frames in all FrameNet

    Args:
        framenet: a FrameNet Object (any version of it from this package will work)

    Returns:
        Dctionary of the form of Lexical Units as keys and sets of Frames related to the LU as values.

    """
    lus2frames = dict()
    for frame in framenet:
        for lu in frame.LUs:
            s = lus2frames.get(lu, set())
            s.add(frame)
            lus2frames[lu] = s
    return lus2frames