@classmethod
def from_buffer(cls, bfr, **kw):
    """ Factory to return a `PacketField` instance from a `CornuCopyBuffer`.

        This default implementation instantiates the instance from
        the value returned by `cls.value_from_buffer(bfr, **kw)`.
    """
    value = cls.value_from_buffer(bfr, **kw)
    return cls(value, **kw)
