code: def test_for(self):
      source = "for i in a:\n    b"
      self.assertDepends(
          source, {("i", "a"), ("b", "a")}, {"a", "b"}, {"i"}
      )
  
imports: from __future__ import print_function
  from __future__ import division
  from __future__ import absolute_import
  import unittest
  import ast
  from ...asttools.visitors.graph_visitor import GraphGen
  from ...asttools.visitors.graph_visitor import DiGraph
  from ...asttools.tests import AllTypesTested, skip_networkx
label_desc: Use image node_id 18 for calling the Test obj's underlying member method code with example usage: obj.test_for() without return types