1 files changed, 28 insertions, 0 deletions
diff --git a/scripts/mbedtls_dev/typing_util.py b/scripts/mbedtls_dev/typing_util.py
new file mode 100644
index 00000000000..2ec448d004a
--- /dev/null
+++ b/scripts/mbedtls_dev/typing_util.py
@@ -0,0 +1,28 @@
+"""Auxiliary definitions used in type annotations.
+"""
+
+# Copyright The Mbed TLS Contributors
+# SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+#
+
+from typing import Any
+
+# The typing_extensions module is necessary for type annotations that are
+# checked with mypy. It is only used for type annotations or to define
+# things that are themselves only used for type annotations. It is not
+# available on a default Python installation. Therefore, try loading
+# what we need from it for the sake of mypy (which depends on, or comes
+# with, typing_extensions), and if not define substitutes that lack the
+# static type information but are good enough at runtime.
+try:
+    from typing_extensions import Protocol #pylint: disable=import-error
+except ImportError:
+    class Protocol: #type: ignore
+        #pylint: disable=too-few-public-methods
+        pass
+
+class Writable(Protocol):
+    """Abstract class for typing hints."""
+    # pylint: disable=no-self-use,too-few-public-methods,unused-argument
+    def write(self, text: str) -> Any:
+        ...