Adde JSON encoder and decoder objects (#499)

stdlib/3/json.pyi

@@ -1,4 +1,4 @@
-from typing import Any, IO, Optional, Tuple, Callable, Dict, List, Union
+from typing import Any, IO, Iterator, Optional, Tuple, Callable, Dict, List, Union
 
 class JSONDecodeError(ValueError):
     def dumps(self, obj: Any) -> str: ...
@@ -49,3 +49,40 @@ def load(fp: IO[str],
     parse_constant: Optional[Callable[[str], Any]] = ...,
     object_pairs_hook: Optional[Callable[[List[Tuple[Any, Any]]], Any]] = ...,
     **kwds: Any) -> Any: ...
+
+class JSONEncoder(object):
+    item_separator = ...  # type: str
+    key_separator = ...  # type: str
+
+    skipkeys = ...  # type: bool
+    ensure_ascii = ...  # type: bool
+    check_circular = ...  # type: bool
+    allow_nan = ...  # type: bool
+    sort_keys = ...  # type: bool
+    indent = None  # type: int
+
+    def __init__(self, skipkeys: bool=..., ensure_ascii: bool=...,
+            check_circular: bool=..., allow_nan: bool=..., sort_keys: bool=...,
+            indent: int=None, separators: Tuple[str, str]=None, default: Callable=None) -> None: ...
+
+    def default(self, o: Any) -> Any: ...
+    def encode(self, o: Any) -> str: ...
+    def iterencode(self, o: Any, _one_shot: bool=False) -> Iterator[str]: ...
+
+class JSONDecoder(object):
+
+    object_hook = None  # type: Callable[[Dict[str, Any]], Any]
+    parse_float = ...  # Callable[[str], Any]
+    parse_int = ...  # Callable[[str], Any]
+    parse_constant = ...  # Callable[[str], Any]
+    strict = ...  # type: bool
+    object_pairs_hook = None  # type: Callable[[List[Tuple[str, Any]]], Any]
+
+    def __init__(self, object_hook: Callable[[Dict[str, Any]], Any]=None,
+            parse_float: Callable[[str], Any]=None,
+            parse_int: Callable[[str], Any]=None,
+            parse_constant: Callable[[str], Any]=None,
+            strict: bool=True,
+            object_pairs_hook: Callable[[List[Tuple[str, Any]]], Any]=None) -> None: ...
+    def decode(self, s: str) -> Any: ...
+    def raw_decode(self, s: str) -> Tuple[Any, int]: ...