class_docstr: Main class from which all Flows should inherit.
  
  Attributes
  ----------
  index
  input
code: def __str__(self):
      step_name = getattr(self, "_current_step", None)
      if step_name:
          index = ",".join(
              str(idx) for idx, _, _ in self.foreach_stack()
          )
          if index:
              inp = self.input
              if inp is None:
                  return "<flow %s step %s[%s]>" % (
                      self.name,
                      step_name,
                      index,
                  )
              else:
                  inp = str(inp)
                  if len(inp) > 20:
                      inp = inp[:20] + "..."
                  return "<flow %s step %s[%s] (input: %s)>" % (
                      self.name,
                      step_name,
                      index,
                      inp,
                  )
          else:
              return "<flow %s step %s>" % (self.name, step_name)
      else:
          return "<flow %s>" % self.name
  
imports: import inspect
  import os
  import sys
  import traceback
  from itertools import islice
  from types import FunctionType, MethodType
  from typing import Any, Callable, List, Optional, Tuple
  from .None import cmd_with_io
  from .parameters import DelayedEvaluationParameter, Parameter
  from .exception import MetaflowException, MissingInMergeArtifactsException, UnhandledInMergeArtifactsException
  from .graph import FlowGraph
  from .unbounded_foreach import UnboundedForeachInput
  from .datastore.inputs import Inputs
label_desc: Use image node_id 16 for calling the FlowSpec obj's underlying member method code with example usage: obj.__str__() and returns: unknown, unknown, unknown, unknown