diff --git a/stdlib/3/inspect.pyi b/stdlib/3/inspect.pyi
index d4fae4b71..9286aa04f 100644
--- a/stdlib/3/inspect.pyi
+++ b/stdlib/3/inspect.pyi
@@ -1,6 +1,7 @@
 # Stubs for inspect
 
 from typing import Any, Tuple, List, Callable
+from types import FrameType
 
 _object = object
 
@@ -29,3 +30,5 @@ class ArgSpec(tuple):
     defaults = ...  # type: tuple
 
 def getargspec(func: object) -> ArgSpec: ...
+
+def stack() -> List[Tuple[FrameType, str, int, str, List[str], int]]: ...
diff --git a/stdlib/3/types.pyi b/stdlib/3/types.pyi
index 866f05d44..80f4ac02c 100644
--- a/stdlib/3/types.pyi
+++ b/stdlib/3/types.pyi
@@ -2,7 +2,7 @@
 
 # TODO this is work in progress
 
-from typing import Any
+from typing import Any, Callable, Dict, Sequence
 
 class ModuleType:
     __name__ = ... # type: str
@@ -12,8 +12,55 @@ class ModuleType:
 class MethodType: ...
 class BuiltinMethodType: ...
 
+class CodeType:
+    """Create a code object.  Not for the faint of heart."""
+    def __init__(self,
+            argcount: int,
+            kwonlyargcount: int,
+            nlocals: int,
+            stacksize: int,
+            flags: int,
+            codestring: bytes,
+            constants: Sequence[Any],
+            names: Sequence[str],
+            varnames: Sequence[str],
+            filename: str,
+            name: str,
+            firstlineno: int,
+            lnotab: bytes,
+            freevars: Sequence[str] = (),
+            cellvars: Sequence[str] = (),
+    ) -> None:
+        self.co_argcount = argcount
+        self.co_kwonlyargcount = kwonlyargcount
+        self.co_nlocals = nlocals
+        self.co_stacksize = stacksize
+        self.co_flags = flags
+        self.co_code = codestring
+        self.co_consts = constants
+        self.co_names = names
+        self.co_varnames = varnames
+        self.co_filename = filename
+        self.co_name = name
+        self.co_firstlineno = firstlineno
+        self.co_lnotab = lnotab
+        self.co_freevars = freevars
+        self.co_cellvars = cellvars
+
+class FrameType:
+    f_back = ... # type: FrameType
+    f_builtins = ... # type: Dict[str, Any]
+    f_code = ... # type: CodeType
+    f_globals = ... # type: Dict[str, Any]
+    f_lasti = ... # type: int
+    f_lineno = ... # type: int
+    f_locals = ... # type: Dict[str, Any]
+    f_trace = ... # type: Callable[[], None]
+
+    def clear(self) -> None: pass
+
 class TracebackType:
-    tb_frame = ... # type: Any
+    tb_frame = ... # type: FrameType
     tb_lasti = ... # type: int
     tb_lineno = ... # type: int
-    tb_next = ... # type: Any
+    tb_next = ... # type: TracebackType