code: def test_exp(self, device, dtype, batch_size):
      theta = self._make_rand_data(device, dtype, (batch_size, 1))
      s = So2.exp(theta)
      self.assert_close(s.z.real, theta.cos())
      self.assert_close(s.z.imag, theta.sin())
  
imports: import pytest
  import torch
  from kornia.geometry.liegroup import So2
  from kornia.geometry.vector import Vector2
  from kornia.testing import BaseTester
label_desc: Use image node_id 13 for calling the TestSo2 obj's underlying member method code with example usage: obj.test_exp(device, dtype, batch_size) without return types