code: def update(self, result: Optional["SubtaskResult"]):
      if result and result.bands:
          bands = self.bands or []
          self.bands = sorted(set(bands + result.bands))
          self.execution_start_time = result.execution_start_time
          if hasattr(result, "execution_end_time"):
              self.execution_end_time = result.execution_end_time
      return self
  
imports: from enum import Enum
  from typing import Iterable, List, Optional, Set, Tuple
  from ...core import ChunkGraph, DAG, ChunkData
  from ...resource import Resource
  from ...serialization.serializables.field_type import TupleType
  from ...serialization.serializables import Serializable, StringField, ReferenceField, Int32Field, Int64Field, Float64Field, BoolField, AnyField, DictField, ListField, TupleField, FieldTypes
  from ...typing import BandType, ChunkType
label_desc: Use image node_id 1 for calling the SubtaskResult obj's underlying member method code with example usage: obj.update(result) and returns: self