code: def test_list_astype():
      s = cudf.Series([[1, 2], [3, 4]])
      s2 = s.list.astype("float64")
      assert s2.dtype == cudf.ListDtype("float64")
      assert_eq(s.list.leaves.astype("float64"), s2.list.leaves)
  
      s = cudf.Series([[[1, 2], [3]], [[5, 6], None]])
      s2 = s.list.astype("string")
      assert s2.dtype == cudf.ListDtype(cudf.ListDtype("string"))
      assert_eq(s.list.leaves.astype("string"), s2.list.leaves)
  
imports: import functools
  import operator
  import numpy
  import pandas
  import pyarrow
  import pytest
  import cudf
  from cudf import NA
  from cudf._lib.copying import get_element
  from cudf.api.types import is_scalar
  from cudf.testing._utils import DATETIME_TYPES, NUMERIC_TYPES, TIMEDELTA_TYPES, assert_eq
label_desc: Use image node_id 42 for calling a global function with example usage: test_list_astype() without return types