Remove dead code and stale Python 2 leftovers (with the help of Claude Fable)

traitlets/config/application.py

@@ -67,7 +67,7 @@
 """.strip()  # trim newlines of front and back
 
 # sys.argv can be missing, for example when python is embedded. See the docs
-# for details: http://docs.python.org/2/c-api/intro.html#embedding-python
+# for details: https://docs.python.org/3/c-api/intro.html#embedding-python
 if not hasattr(sys, "argv"):
     sys.argv = [""]
 

traitlets/config/loader.py

@@ -77,11 +77,6 @@ def print_help(self, file: t.Any = None) -> None:
 # -----------------------------------------------------------------------------
 
 
-def execfile(fname: str, glob: dict[str, Any]) -> None:
-    with open(fname, "rb") as f:
-        exec(compile(f.read(), fname, "exec"), glob, glob)  # noqa: S102
-
-
 class LazyConfigValue(HasTraits):
     """Proxy object for exposing methods on configurable containers
 
@@ -250,10 +245,6 @@ def _ensure_subconfig(self) -> None:
             if _is_section_key(key) and isinstance(obj, dict) and not isinstance(obj, Config):
                 setattr(self, key, Config(obj))
 
-    def _merge(self, other: t.Any) -> None:
-        """deprecated alias, use Config.merge()"""
-        self.merge(other)
-
     def merge(self, other: t.Any) -> None:
         """merge another config object into this one"""
         to_update = {}

traitlets/traitlets.py

@@ -62,9 +62,6 @@
 
 SequenceTypes = (list, tuple, set, frozenset)
 
-# backward compatibility, use to differ between Python 2 and 3.
-ClassTypes = (type,)
-
 if t.TYPE_CHECKING:
     from typing_extensions import TypeVar
 else: