in dataset/transform.py [0:0]
    def __call__(self, data):
        """Perform transformation
        Arguments:
            data {dict} -- frame data
        """
        if 'joints3D' not in list(data.keys()):
            return data
        p3d = data['joints3D']
        joint_zeroed = p3d[self.jid_zeroed][np.newaxis]
        # update p3d
        p3d -= joint_zeroed
        data.update({'joints3D': p3d})
        return data