class_docstr: Diffeomorphism between S1 and SO2.
class_docstr_tok: ["Diffeomorphism","between","S1","and","SO2","."]
code: def diffeomorphism(self, base_point):
      second_column = gs.stack(
          [-base_point[..., 1], base_point[..., 0]], axis=-1
      )
      return gs.stack([base_point, second_column], axis=-1)
  
imports: import pytest
  import geomstats.backend
  from geomstats.geometry.diffeo import AutodiffDiffeo
  from geomstats.test.random import RandomDataGenerator
  from geomstats.test.test_case import TestCase
  from geomstats.test.vectorization import generate_vectorization_data
label_desc: Use image node_id 2 for calling the CircleSO2Diffeo obj's underlying member method code with example usage: obj.diffeomorphism(base_point) and returns: gs