code: def test_mul_vector(self, device, dtype, batch_size):
      s1 = So2.identity(batch_size, device, dtype)
      if batch_size is None:
          shape = ()
      else:
          shape = (batch_size,)
      t1 = Vector2.random(shape, device, dtype)
      t2 = Vector2.random(shape, device, dtype)
      self.assert_close((s1 * t1), t1)
      self.assert_close(
          (So2.identity(device=device, dtype=dtype) * t2), t2
      )
  
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 12 for calling the TestSo2 obj's underlying member method code with example usage: obj.test_mul_vector(device, dtype, batch_size) without return types