py_gen: move TLVs into their own module
diff --git a/lang_python.py b/lang_python.py
index 9087b43..019b62d 100644
--- a/lang_python.py
+++ b/lang_python.py
@@ -85,7 +85,7 @@
     1: ["action", "common", "const", "message", "util"],
     2: ["action", "common", "const", "instruction", "message", "util"],
     3: ["action", "common", "const", "instruction", "message", "oxm", "util"],
-    4: ["action", "action_id", "common", "const", "instruction", "instruction_id", "message", "meter_band", "oxm", "util"],
+    4: ["action", "action_id", "common", "const", "instruction", "instruction_id", "message", "meter_band", "oxm", "bsn_tlv", "util"],
 }
 
 def make_gen(name, version):
diff --git a/py_gen/codegen.py b/py_gen/codegen.py
index de3fdba..44b4814 100644
--- a/py_gen/codegen.py
+++ b/py_gen/codegen.py
@@ -45,6 +45,7 @@
     'of_instruction': 'instruction',
     'of_instruction_id': 'instruction_id',
     'of_meter_band': 'meter_band',
+    'of_bsn_tlv': 'bsn_tlv',
 }
 
 # Return the module and class names for the generated Python class
@@ -123,6 +124,11 @@
 def generate_util(out, name, version):
     util.render_template(out, 'util.py', version=version)
 
+def generate_bsn_tlv(out, name, version):
+    util.render_template(out, 'module.py',
+                         ofclasses=modules_by_version[version]['bsn_tlv'],
+                         version=version)
+
 def init():
     for version in loxi_globals.OFVersions.target_versions:
         modules_by_version[version] = build_ofclasses(version)
diff --git a/py_gen/templates/init.py b/py_gen/templates/init.py
index f66e62a..3b73baa 100644
--- a/py_gen/templates/init.py
+++ b/py_gen/templates/init.py
@@ -38,6 +38,7 @@
 :: #endif
 :: if version >= 4:
 import meter_band
+import bsn_tlv
 :: #endif
 from const import *
 from common import *
diff --git a/py_gen/templates/module.py b/py_gen/templates/module.py
index 30c45ad..02f0002 100644
--- a/py_gen/templates/module.py
+++ b/py_gen/templates/module.py
@@ -46,6 +46,7 @@
 import action_id
 import instruction_id
 import meter_band
+import bsn_tlv
 :: #endif
 import util
 import loxi.generic_util