code: def _execute_map(cls, ctx, op):
      out = op.outputs[0]
  
      df = ctx[op.input.key]
      sio = StringIO()
      header = op.header if out.index[0] == 0 else False
      # do not output header if index of chunk > 0
      cls._to_csv(op, df, sio, header=header)
  
      ret = sio.getvalue().encode(op.encoding or "utf-8")
      ctx[op.outputs[0].key] = ret
      ctx[op.outputs[1].key] = len(ret)
  
imports: from io import StringIO
  import numpy
  import pandas
  from ...None import opcodes
  from ...core import OutputType, recursive_tile
  from ...core.operand import OperandStage
  from ...lib.filesystem import open_file
  from ...serialization.serializables import KeyField, AnyField, StringField, ListField, BoolField, Int32Field, Int64Field, DictField
  from ...tensor.core import TensorOrder
  from ...tensor.operands import TensorOperand, TensorOperandMixin
  from ..operands import DataFrameOperand, DataFrameOperandMixin
  from ..utils import parse_index
label_desc: Use image node_id 30 for calling the DataFrameToCSV obj's underlying member method code with example usage: obj._execute_map(cls, ctx, op) without return types