add _sha256.pyi

builtins/2.7/_sha256.pyi

@@ -0,0 +1,19 @@
+class sha224(object):
+    name = ...  # type: str
+    block_size = ...  # type: int
+    digest_size = ...  # type: int
+    digestsize = ...  # type: int
+    def copy(self) -> "sha224": ...
+    def digest(self) -> str: ...
+    def hexdigest(self) -> str: ...
+    def update(self, arg: str) -> None: ...
+
+class sha256(object):
+    name = ...  # type: str
+    block_size = ...  # type: int
+    digest_size = ...  # type: int
+    digestsize = ...  # type: int
+    def copy(self) -> "sha256": ...
+    def digest(self) -> str: ...
+    def hexdigest(self) -> str: ...
+    def update(self, arg: str) -> None: ...