hashlib: fix arguments (#3626)

* hashlib: fix argument names
* hashlib: add default values to scrypt, make args Optional

Author: hauntsaninja

stdlib/3/hashlib.pyi

@@ -21,12 +21,20 @@ class _Hash(object):
     def hexdigest(self) -> str: ...
     def update(self, arg: _DataType) -> None: ...
 
-def md5(arg: _DataType = ...) -> _Hash: ...
-def sha1(arg: _DataType = ...) -> _Hash: ...
-def sha224(arg: _DataType = ...) -> _Hash: ...
-def sha256(arg: _DataType = ...) -> _Hash: ...
-def sha384(arg: _DataType = ...) -> _Hash: ...
-def sha512(arg: _DataType = ...) -> _Hash: ...
+if sys.version_info >= (3, 8):
+    def md5(string: _DataType = ...) -> _Hash: ...
+    def sha1(string: _DataType = ...) -> _Hash: ...
+    def sha224(string: _DataType = ...) -> _Hash: ...
+    def sha256(string: _DataType = ...) -> _Hash: ...
+    def sha384(string: _DataType = ...) -> _Hash: ...
+    def sha512(string: _DataType = ...) -> _Hash: ...
+else:
+    def md5(__string: _DataType = ...) -> _Hash: ...
+    def sha1(__string: _DataType = ...) -> _Hash: ...
+    def sha224(__string: _DataType = ...) -> _Hash: ...
+    def sha256(__string: _DataType = ...) -> _Hash: ...
+    def sha384(__string: _DataType = ...) -> _Hash: ...
+    def sha512(__string: _DataType = ...) -> _Hash: ...
 
 def new(name: str, data: _DataType = ...) -> _Hash: ...
 
@@ -55,7 +63,7 @@ if sys.version_info >= (3, 6):
     shake_128 = _VarLenHash
     shake_256 = _VarLenHash
 
-    def scrypt(password: _DataType, *, salt: _DataType, n: int, r: int, p: int, maxmem: int = ..., dklen: int = ...) -> bytes: ...
+    def scrypt(password: _DataType, *, salt: Optional[_DataType] = ..., n: Optional[int] = ..., r: Optional[int] = ..., p: Optional[int] = ..., maxmem: int = ..., dklen: int = ...) -> bytes: ...
 
     class _BlakeHash(_Hash):
         MAX_DIGEST_SIZE: int