code: def _execute_map(cls, ctx, op: "StatsModelsTrain"):
      endog = ctx[op.endog.key]
      exog = ctx[op.exog.key]
  
      # code from statsmodels.base.distributed_estimation::_helper_fit_partition
      model = op.model_class(endog, exog, **op.init_kwds)
      results = op.estimation_method(
          model,
          op.partition_id,
          op.num_partitions,
          fit_kwds=op.fit_kwds,
          **op.estimation_kwds,
      )
      ctx[op.outputs[0].key] = pickle.dumps(results)
  
imports: import pickle
  import cloudpickle
  from ....None import opcodes
  from ....core import OutputType, recursive_tile
  from ....core.context import get_context
  from ....core.operand import OperandStage, MergeDictOperand
  from ....serialization.serializables import KeyField, BytesField, DictField, Int32Field, Float32Field, FunctionField
  from ....utils import has_unknown_shape
label_desc: Use image node_id 19 for calling the StatsModelsTrain obj's underlying member method code with example usage: obj._execute_map(cls, ctx, op) without return types