more 3.7 features (#2017)

stdlib/2and3/struct.pyi

@@ -27,7 +27,10 @@ if sys.version_info >= (3, 4):
 def calcsize(fmt: _FmtType) -> int: ...
 
 class Struct:
-    format = ...  # type: bytes
+    if sys.version_info >= (3, 7):
+        format: str
+    else:
+        format: bytes
     size = ...  # type: int
 
     def __init__(self, format: _FmtType) -> None: ...

stdlib/3/_ast.pyi

@@ -1,4 +1,4 @@
-# Python 3.5 _ast
+import sys
 import typing
 from typing import Any, Optional, Union
 
@@ -16,6 +16,8 @@ class mod(AST):
 
 class Module(mod):
     body = ...  # type: typing.List[stmt]
+    if sys.version_info >= (3, 7):
+        docstring: Optional[str]
 
 class Interactive(mod):
     body = ...  # type: typing.List[stmt]
@@ -37,6 +39,8 @@ class FunctionDef(stmt):
     body = ...  # type: typing.List[stmt]
     decorator_list = ...  # type: typing.List[expr]
     returns = ...  # type: Optional[expr]
+    if sys.version_info >= (3, 7):
+        docstring: Optional[str]
 
 class AsyncFunctionDef(stmt):
     name = ...  # type: _identifier
@@ -44,6 +48,8 @@ class AsyncFunctionDef(stmt):
     body = ...  # type: typing.List[stmt]
     decorator_list = ...  # type: typing.List[expr]
     returns = ...  # type: Optional[expr]
+    if sys.version_info >= (3, 7):
+        docstring: Optional[str]
 
 class ClassDef(stmt):
     name = ...  # type: _identifier
@@ -51,6 +57,8 @@ class ClassDef(stmt):
     keywords = ...  # type: typing.List[keyword]
     body = ...  # type: typing.List[stmt]
     decorator_list = ...  # type: typing.List[expr]
+    if sys.version_info >= (3, 7):
+        docstring: Optional[str]
 
 class Return(stmt):
     value = ...  # type: Optional[expr]

stdlib/3/types.pyi

@@ -175,6 +175,9 @@ class FrameType:
     f_lineno = ...  # type: int
     f_locals = ...  # type: Dict[str, Any]
     f_trace = ...  # type: Callable[[], None]
+    if sys.version_info >= (3, 7):
+        f_frace_lines: bool
+        f_trace_opcodes: bool
 
     def clear(self) -> None: ...