constant.diff

diff --git a/src/twisted/internet/_sslverify.py b/src/twisted/internet/_sslverify.py
index b62ccc5..7535297 100644
--- a/src/twisted/internet/_sslverify.py
+++ b/src/twisted/internet/_sslverify.py
@@ -24,32 +24,27 @@ from twisted.python._oldstyle import _oldStyle
 from ._idna import _idnaBytes
 
 
+import attr
 
-
-class TLSVersion(Names):
-    """
-    TLS versions that we can negotiate with the client/server.
-    """
-    SSLv3 = NamedConstant()
-    TLSv1_0 = NamedConstant()
-    TLSv1_1 = NamedConstant()
-    TLSv1_2 = NamedConstant()
-    TLSv1_3 = NamedConstant()
+@attr.s
+class _TLSData(object):
+    disableFlag = attr.ib(
 
 
 
-_tlsDisableFlags = {
-    TLSVersion.SSLv3: SSL.OP_NO_SSLv3,
-    TLSVersion.TLSv1_0: SSL.OP_NO_TLSv1,
-    TLSVersion.TLSv1_1: SSL.OP_NO_TLSv1_1,
-    TLSVersion.TLSv1_2: SSL.OP_NO_TLSv1_2,
 
+class TLSVersion(Values):
+    """
+    TLS versions that we can negotiate with the client/server.
+    """
+    SSLv3 = ValueConstant(_TLSData(disableFlag=SSL.OP_NO_SSLv3))
+    TLSv1_0 = ValueConstant(_TLSData(disableFlag=SSL.OP_NO_TLSv1,  ))
+    TLSv1_1 = ValueConstant(_TLSData(disableFlag=SSL.OP_NO_TLSv1_1,))
+    TLSv1_2 = ValueConstant(_TLSData(disableFlag=SSL.OP_NO_TLSv1_2,))
     # If we don't have TLS v1.3 yet, we can't disable it -- this is just so
     # when it makes it into OpenSSL, connections knowingly bracketed to v1.2
     # don't end up going to v1.3
-    TLSVersion.TLSv1_3: getattr(SSL, "OP_NO_TLSv1_3", 0x00),
-}
-
+    TLSv1_3 = ValueConstant(_TLSData(disableFlag=getattr(SSL, "OP_NO_TLSv1_3", 0x00)))
 
 
 def _getExcludedTLSProtocols(oldest, newest):