fix bugs in stdlib/2/csv.py (#932)

Author: matthiaskramm

stdlib/2/csv.pyi

@@ -2,7 +2,7 @@
 #
 # NOTE: Based on a dynamically typed stub automatically generated by stubgen.
 
-from typing import Any, Dict, Iterable, List, Sequence, Union
+from typing import Any, Dict, Iterable, List, Sequence, Type, Union
 
 # Public interface of _csv.reader's return type
 class _Reader(Iterable[List[str]]):
@@ -11,7 +11,7 @@ class _Reader(Iterable[List[str]]):
 
     def next(self) -> List[str]: ...
 
-_Row = Sequence[Union[str, int]]
+_Row = Sequence[Any]  # May contain anything: csv calls str() on the elements that are not None
 
 # Public interface of _csv.writer's return type
 class _Writer:
@@ -27,7 +27,7 @@ QUOTE_NONNUMERIC = ...  # type: int
 
 class Error(Exception): ...
 
-_Dialect = Union[str, Dialect]
+_Dialect = Union[str, Dialect, Type[Dialect]]
 
 def writer(csvfile: Any, dialect: _Dialect = ..., **fmtparams) -> _Writer: ...
 def reader(csvfile: Iterable[str], dialect: _Dialect = ..., **fmtparams) -> _Reader: ...
@@ -66,7 +66,7 @@ class DictReader(Iterable):
     def __init__(self, f: Iterable[str], fieldnames: Sequence[Any] = ..., restkey=...,
                  restval=..., dialect: _Dialect = ..., *args, **kwds) -> None: ...
     def __iter__(self): ...
-    def __next__(self): ...
+    def next(self): ...
 
 _DictRow = Dict[Any, Union[str, int]]