message: return the visit result in the CodeGenerator
diff: @@ -527,7 +527,7 @@ class CodeGenerator(NodeStateTracker, gast.NodeVisitor):
  self.ctx.current_origin = anno.getanno(node, anno.Basic.ORIGIN)
  try:
  - super(CodeGenerator, self).visit(node)
  + ret = super(CodeGenerator, self).visit(node)
  # By default, all replacements receive the origin info of the replaced
  # node.
  @@ -537,5 +537,6 @@ class CodeGenerator(NodeStateTracker, gast.NodeVisitor):
  node, anno.Basic.ORIGIN, default=parent_origin)
  if inherited_origin is not None:
  self.source_map[(eof_before, eof_after)] = inherited_origin
  + return ret
  finally:
  self.ctx.current_origin = parent_origin
  