code: def execute(cls, ctx, op):
      chunk = op.outputs[0]
      shard = op.mldataset.get_shard(chunk.index[0])
      pd_dfs = list(shard)
      pd_df = pd.concat(pd_dfs).set_index(chunk.index_value.to_pandas())
      ctx[chunk.key] = pd_df
  
imports: import functools
  import warnings
  import numpy
  import pandas
  from ...None import opcodes
  from ...core import OutputType
  from ...serialization.serializables import AnyField, BoolField, ListField, Int64Field, ReferenceField
  from ..utils import parse_index, lazy_import, tokenize
  from .core import IncrementalIndexDatasource, IncrementalIndexDataSourceMixin, HeadOptimizedDataSource
label_desc: Use image node_id 5 for calling the DataFrameReadMLDataset obj's underlying member method code with example usage: obj.execute(cls, ctx, op) without return types