code: def test_add(self):
      pval = MockMemory.cur_ptr
      memptr = mock_alloc(8)
  
      memptr2 = memptr + 4
      assert isinstance(memptr2, pinned_memory.PinnedMemoryPointer)
      assert pval + 4 == int(memptr2)
  
      memptr3 = 4 + memptr
      assert isinstance(memptr3, pinned_memory.PinnedMemoryPointer)
      assert pval + 4 == int(memptr3)
  
      memptr += 4
      assert isinstance(memptr, pinned_memory.PinnedMemoryPointer)
      assert pval + 4 == int(memptr)
  
imports: import unittest
  from cupy.cuda import pinned_memory
label_desc: Use image node_id 2 for calling the TestMemoryPointer obj's underlying member method code with example usage: obj.test_add() without return types