rotate matrix question

[buaazeus]

Hello，As I know, the inverse and transpose of a rotate matrix will be the same. So, transpose of inverse matrix will be itself.
In obtain_sensor2top of mmdetection3d/blob/master/tools/data_converter/nuscenes_converter.py,
there is code like
np.linalg.inv(e2g_r_mat).T
np.linalg.inv(l2e_r_mat).T
actually they equals e2g_r_mat and l2e_r_mat.
Question is what is the meaning of np.linalg.inv().T ops?
Anyone could help to explain?
Thank you!