docs: def get_field(self, state, field_name, field_type):
          """
          Gets the value of an instance field.
          """
          # get field reference
          field_ref = SimSootValue_InstanceFieldRef.get_ref(state=state,
                                                            obj_alloc_id=self.heap_alloc_id,
                                                            field_class_name=self.type,
                                                            field_name=field_name,
                                                            field_type=field_type)
          # load value from java memory
          return state.memory.load(field_ref, none_if_missing=True)