code: def test_serialize_deserialize_dtype():
      data = F.copy_to(
          F.tensor(
              [
                  [1.0, 1.0, 1.0, 1.0],
                  [0.0, 2.0, 9.0, 0.0],
                  [3.0, 2.0, 1.0, 0.0],
                  [1.0, 1.0, 1.0, 1.0],
                  [0.0, 2.0, 4.0, 0.0],
              ]
          ),
          F.ctx(),
      )
      original = Column(data)
      original = original.astype(F.int64)
  
      serial = pickle.dumps(original)
      new = pickle.loads(serial)
  
      assert new.dtype == F.int64
  
file_path: dgl/tests/python/common/test_frame.py
imports: import pickle
  import unittest
  import backend
  import dgl
  import dgl.ndarray
  import numpy
  from dgl.frame import Column
  from utils import parametrize_idtype
label_desc: Use image node_id 4 for calling a global function with example usage: test_serialize_deserialize_dtype() without return types