'Create a new :class:`BboxTransformTo` that linearly transforms
points from the unit bounding box to *boxout*.'

def __init__(self, boxout, **kwargs):

    if (not boxout.is_bbox):
        raise ValueError(u"'boxout'    must    be    bbox")
    Affine2DBase.__init__(self, **kwargs)
    self._boxout = boxout
    self.set_children(boxout)
    self._mtx = None
    self._inverted = None
