message: Mark the main AutoGraph target as Py3-only.
diff: @@ -21,7 +21,7 @@ py_strict_library(
  srcs = [
  "__init__.py",
  ],
  - srcs_version = "PY2AND3",
  + srcs_version = "PY3",
  visibility = ["//visibility:public"],
  deps = [
  "//tensorflow/python:util",
  