code: def test_double_free(self):
      mem = self.pool.malloc(1).mem
      mem.free()
      mem.free()
  
imports: import unittest
  from cupy.cuda import pinned_memory
label_desc: Use image node_id 8 for calling the TestSingleDeviceMemoryPool obj's underlying member method code with example usage: obj.test_double_free() without return types