code: def __len__(self) -> int:
      return self.num_steps
  
imports: import logging
  import numpy
  import pandas
  from typing import Optional, Union, Callable, List, TYPE_CHECKING, Any, Tuple
  from .PlotterBase import Plottable
  from .compute.ComputeMixin import ComputeMixin
label_desc: Use image node_id 2 for calling the SubgraphIterator obj's underlying member method code with example usage: obj.__len__() and returns: self