code: def test_null_copy():
      col = Series(np.arange(2049))
      col[:] = None
      assert len(col) == 2049
  
imports: import cupy
  import numpy
  import pandas
  import pytest
  import cudf
  from cudf import Series
  from cudf.testing._utils import NUMERIC_TYPES, OTHER_TYPES, assert_eq
label_desc: Use image node_id 5 for calling a global function with example usage: test_null_copy() without return types