class_docstr: Test propagation of exceptions
code: def __init__(self, seqn):
      self.seqn = seqn
      self.i = 0
  
imports: import unittest
  import sys
  import pickle
  from test import support
  from test.support import ALWAYS_EQ, NEVER_EQ
  from itertools import chain
label_desc: Use image node_id 1 to create a new IterGenExc object  with example: obj = IterGenExc(seqn)