code: def memory_usage(self):
      n = 0
      if self.nullable:
          n += cudf._lib.null_mask.bitmask_allocation_size_bytes(
              self.size
          )
  
      child0_size = (self.size + 1) * self.base_children[
          0
      ].dtype.itemsize
      current_base_child = self.base_children[1]
      current_offset = self.offset
      n += child0_size
      while type(current_base_child) is ListColumn:
          child0_size = (
              current_base_child.size + 1 - current_offset
          ) * current_base_child.base_children[0].dtype.itemsize
          current_offset = current_base_child.base_children[
              0
          ].element_indexing(current_offset)
          n += child0_size
          current_base_child = current_base_child.base_children[1]
  
      n += (
          current_base_child.size - current_offset
      ) * current_base_child.dtype.itemsize
  
      if current_base_child.nullable:
          n += cudf._lib.null_mask.bitmask_allocation_size_bytes(
              current_base_child.size
          )
      return n
  
imports: from __future__ import annotations
  from functools import cached_property
  from typing import List, Optional, Sequence, Tuple, Union
  import numpy
  import pyarrow
  from typing_extensions import Self
  import cudf
  from cudf._lib.copying import segmented_gather
  from cudf._lib.lists import concatenate_list_elements, concatenate_rows, contains_scalar, count_elements, distinct, extract_element_column, extract_element_scalar, index_of_column, index_of_scalar, sort_lists
  from cudf._lib.strings.convert.convert_lists import format_list_column
  from cudf._lib.types import size_type_dtype
  from cudf._typing import ColumnBinaryOperand, ColumnLike, Dtype, ScalarLike
  from cudf.api.types import _is_non_decimal_numeric_dtype, is_scalar
  from cudf.core.column import ColumnBase, as_column, column
  from cudf.core.column.methods import ColumnMethods, ParentType
  from cudf.core.dtypes import ListDtype
  from cudf.core.missing import NA
label_desc: Use image node_id 2 for calling the ListColumn obj's underlying member method code with example usage: obj.memory_usage() and returns: n