Fix typings

Author: A5rocks

src/trustme/__init__.py

@@ -8,7 +8,7 @@
 from contextlib import contextmanager
 from enum import Enum
 from tempfile import NamedTemporaryFile
-from typing import TYPE_CHECKING, Generator, List, Optional, Union
+from typing import TYPE_CHECKING, Generator, List, Optional, Union, cast
 
 import idna
 from cryptography import x509
@@ -545,13 +545,14 @@ def configure_cert(self, ctx: Union[ssl.SSLContext, OpenSSL.SSL.Context]) -> Non
             with self.private_key_and_cert_chain_pem.tempfile() as path:
                 ctx.load_cert_chain(path)
         elif _smells_like_pyopenssl(ctx):
+            octx = cast("OpenSSL.SSL.Context", ctx)
             key = load_pem_private_key(self.private_key_pem.bytes(), None)
-            ctx.use_privatekey(key)
+            octx.use_privatekey(key)
             cert = x509.load_pem_x509_certificate(self.cert_chain_pems[0].bytes())
-            ctx.use_certificate(cert)
+            octx.use_certificate(cert)
             for pem in self.cert_chain_pems[1:]:
                 cert = x509.load_pem_x509_certificate(pem.bytes())
-                ctx.add_extra_chain_cert(cert)
+                octx.add_extra_chain_cert(cert)
         else:
             raise TypeError(
                 "unrecognized context type {!r}".format(ctx.__class__.__name__)