code: def checked_base_output(self) -> BaseOutput:  # noqa: D
      assert (
          self.base_output_node
      ), f"Expected the result of traversal to produce a {BaseOutput}"
      return self.base_output_node
  
imports: from __future__ import annotations
  import logging
  from dataclasses import dataclass
  from typing import List, Optional, Sequence
  from metricflow.dag.id_generation import OPTIMIZED_DATAFLOW_PLAN_PREFIX, IdGeneratorRegistry
  from metricflow.dataflow.dataflow_plan import AddGeneratedUuidColumnNode, AggregateMeasuresNode, BaseOutput, CombineAggregatedOutputsNode, ComputeMetricsNode, ConstrainTimeRangeNode, DataflowPlan, DataflowPlanNode, DataflowPlanNodeVisitor, FilterElementsNode, JoinConversionEventsNode, JoinOverTimeRangeNode, JoinToBaseOutputNode, JoinToTimeSpineNode, MetricTimeDimensionTransformNode, MinMaxNode, OrderByLimitNode, ReadSqlSourceNode, SemiAdditiveJoinNode, SinkOutput, WhereConstraintNode, WriteToResultDataframeNode, WriteToResultTableNode
  from metricflow.dataflow.dataflow_plan_to_text import dataflow_dag_as_text
  from metricflow.dataflow.optimizer.dataflow_plan_optimizer import DataflowPlanOptimizer
  from metricflow.dataflow.optimizer.source_scan.cm_branch_combiner import ComputeMetricsBranchCombiner, ComputeMetricsBranchCombinerResult
label_desc: Use image node_id 1 for calling the OptimizeBranchResult obj's underlying member method code with example usage: obj.checked_base_output() and returns: self