class_docstr: Create a graph from the execution flow of the ast
class_docstr_tok: ["Create","a","graph","from","the","execution","flow","of","the","ast"]
code: def visitLambda(self, node):
      gen = GraphGen()
      gen.visit_lambda(node)
  
      for undef in gen.undefined:
          if not self.graph.has_node(undef):
              self.graph.add_node(undef)
  
      return gen.undefined
  
imports: from __future__ import print_function
  from __future__ import division
  from __future__ import absolute_import
  from ...asttools import Visitor, visit_children
  import _ast
  from ...asttools.visitors.symbol_visitor import get_symbols
label_desc: Use image node_id 3 for calling the GraphGen obj's underlying member method code with example usage: obj.visitLambda(node) and returns: gen