1 files changed, 21 insertions, 0 deletions
diff --git a/Lib/warnings.py b/Lib/warnings.py
index 691ccddfa45..887ca6ecd1a 100644
--- a/Lib/warnings.py
+++ b/Lib/warnings.py
@@ -483,6 +483,27 @@ class catch_warnings(object):
         self._module._showwarnmsg_impl = self._showwarnmsg_impl
 
 
+_DEPRECATED_MSG = "{name!r} is deprecated and slated for removal in Python {remove}"
+
+def _deprecated(name, message=_DEPRECATED_MSG, *, remove, _version=sys.version_info):
+    """Warn that *name* is deprecated or should be removed.
+
+    RuntimeError is raised if *remove* specifies a major/minor tuple older than
+    the current Python version or the same version but past the alpha.
+
+    The *message* argument is formatted with *name* and *remove* as a Python
+    version (e.g. "3.11").
+
+    """
+    remove_formatted = f"{remove[0]}.{remove[1]}"
+    if (_version[:2] > remove) or (_version[:2] == remove and _version[3] != "alpha"):
+        msg = f"{name!r} was slated for removal after Python {remove_formatted} alpha"
+        raise RuntimeError(msg)
+    else:
+        msg = message.format(name=name, remove=remove_formatted)
+        warn(msg, DeprecationWarning, stacklevel=3)
+
+
 # Private utility function called by _PyErr_WarnUnawaitedCoroutine
 def _warn_unawaited_coroutine(coro):
     msg_lines = [