code: def _execute_subset_tree_map(cls, ctx, op):
      out = op.outputs[0]
      idx = out.index[0]
      inp = ctx[op.input.key]
      xdf = cls._get_xdf(inp)
  
      # index would be (chunk_index, i)
      index = xdf.MultiIndex.from_arrays(
          [np.full(inp.shape[0], idx), np.arange(inp.shape[0])],
          names=["_chunk_index_", "_i_"],
      )
      inp = inp.set_index(index)
      ctx[out.key] = cls._drop_duplicates(inp, op, ignore_index=False)
  
imports: import inspect
  import numpy
  import pandas
  from pandas.api.types import is_list_like
  from ...config import options
  from ...core import OutputType, recursive_tile
  from ...core.operand import OperandStage, MapReduceOperand
  from ...serialization.serializables import AnyField, Int32Field, StringField, KeyField
  from ...utils import ceildiv, has_unknown_shape, lazy_import
  from ..initializer import DataFrame
  from ..operands import DataFrameOperandMixin, DataFrameShuffleProxy
label_desc: Use image node_id 21 for calling the DuplicateOperand obj's underlying member method code with example usage: obj._execute_subset_tree_map(cls, ctx, op) without return types