def collect_loop_vars(self, loop_vars, loop_body):
    for stmt in loop_body:
      assert stmt.__class__ in (Assign, If, ExprStmt), \
        "Unexpected statement in simple block: %s" % stmt 
      if stmt.__class__ is Assign:
        lhs_names = collect_binding_names(stmt.lhs)
        rhs_names = collect_var_names(stmt.rhs)
        if any(name in loop_vars for name in rhs_names):
          loop_vars.update(lhs_names)
Test if the address is unspecified.
dataset/ETHPy150Open iskandr/parakeet/parakeet/transforms/loop_transform.py/LoopTransform.collect_loop_vars--crossover with--dataset/ETHPy150Open anandology/pyjamas/pyjs/src/pyjs/lib/ipaddr.py/_BaseV6.is_unspecified