Improve csv module and float() signature (#1418)

* DictReader should not be abstract. Reformat long lines.
* Make restval optional for DictWriter.__init__.
* The arg to reader() is *Iterable*, not *Iterator*.
* Improve signature of float() (use Union instead of overload).

stdlib/2/__builtin__.pyi

@@ -144,14 +144,7 @@ class int(SupportsInt, SupportsFloat, SupportsAbs[int]):
     def __nonzero__(self) -> bool: ...
 
 class float(SupportsFloat, SupportsInt, SupportsAbs[float]):
-    @overload
-    def __init__(self) -> None: ...
-    @overload
-    def __init__(self, x: SupportsFloat) -> None: ...
-    @overload
-    def __init__(self, x: unicode) -> None: ...
-    @overload
-    def __init__(self, x: bytearray) -> None: ...
+    def __init__(self, x: Union[SupportsFloat, str, unicode, bytearray] = ...) -> None: ...
     def as_integer_ratio(self) -> Tuple[int, int]: ...
     def hex(self) -> str: ...
     def is_integer(self) -> bool: ...

stdlib/2and3/_csv.pyi

@@ -37,7 +37,7 @@ class _writer:
 
 # TODO: precise type
 def writer(csvfile: Any, dialect: Any = ..., **fmtparams: Any) -> _writer: ...
-def reader(csvfile: Iterator[str], dialect: Any = ..., **fmtparams: Any) -> _reader: ...
+def reader(csvfile: Iterable[str], dialect: Any = ..., **fmtparams: Any) -> _reader: ...
 def register_dialect(name: str, dialect: Any = ..., **fmtparams: Any) -> None: ...
 def unregister_dialect(name: str) -> None: ...
 def get_dialect(name: str) -> Dialect: ...

stdlib/2and3/csv.pyi

@@ -2,12 +2,26 @@ from collections import OrderedDict
 import sys
 from typing import Any, Dict, Iterable, Iterator, List, Optional, Sequence, Union
 
-from _csv import _reader, _writer, reader as reader, writer as writer, register_dialect as register_dialect, unregister_dialect as unregister_dialect, get_dialect as get_dialect, list_dialects as list_dialects, field_size_limit as field_size_limit, QUOTE_ALL as QUOTE_ALL, QUOTE_MINIMAL as QUOTE_MINIMAL, QUOTE_NONE as QUOTE_NONE, QUOTE_NONNUMERIC as QUOTE_NONNUMERIC, Error as Error
+from _csv import (_reader,
+                  _writer,
+                  reader as reader,
+                  writer as writer,
+                  register_dialect as register_dialect,
+                  unregister_dialect as unregister_dialect,
+                  get_dialect as get_dialect,
+                  list_dialects as list_dialects,
+                  field_size_limit as field_size_limit,
+                  QUOTE_ALL as QUOTE_ALL,
+                  QUOTE_MINIMAL as QUOTE_MINIMAL,
+                  QUOTE_NONE as QUOTE_NONE,
+                  QUOTE_NONNUMERIC as QUOTE_NONNUMERIC,
+                  Error as Error,
+                  )
 
 _Dialect = Union[str, Dialect]
 _DictRow = Dict[str, Any]
 
-class Dialect:
+class Dialect(object):
     delimiter = ...  # type: str
     quotechar = ...  # type: Optional[str]
     escapechar = ...  # type: Optional[str]
@@ -45,7 +59,11 @@ if sys.version_info >= (3, 6):
         dialect = ...  # type: _Dialect
         line_num = ...  # type: int
         fieldnames = ...  # type: Sequence[str]
-        def __init__(self, f: Iterator[str], fieldnames: Sequence[str] = ..., restkey: Optional[str] = ..., restval: Optional[str] = ..., dialect: _Dialect = ..., *args: Any, **kwds: Any) -> None: ...
+        def __init__(self, f: Iterator[str], fieldnames: Sequence[str] = ...,
+                     restkey: Optional[str] = ..., restval: Optional[str] = ..., dialect: _Dialect = ...,
+                     *args: Any, **kwds: Any) -> None: ...
+        def __iter__(self) -> Iterator[OrderedDict[str, str]]: ...
+        def next(self) -> OrderedDict[str, str]: ...
 else:
     class DictReader(Iterator[Dict[str, str]]):
         restkey = ...  # type: Optional[str]
@@ -54,19 +72,25 @@ else:
         dialect = ...  # type: _Dialect
         line_num = ...  # type: int
         fieldnames = ...  # type: Sequence[str]
-        def __init__(self, f: Iterator[str], fieldnames: Sequence[str] = ..., restkey: Optional[str] = ..., restval: Optional[str] = ..., dialect: _Dialect = ..., *args: Any, **kwds: Any) -> None: ...
+        def __init__(self, f: Iterator[str], fieldnames: Sequence[str] = ...,
+                     restkey: Optional[str] = ..., restval: Optional[str] = ..., dialect: _Dialect = ...,
+                     *args: Any, **kwds: Any) -> None: ...
+        def __iter__(self) -> Iterator[OrderedDict[str, str]]: ...
+        def next(self) -> OrderedDict[str, str]: ...
 
-class DictWriter:
+class DictWriter(object):
     fieldnames = ...  # type: Sequence[str]
     restval = ...  # type: Optional[Any]
     extrasaction = ...  # type: str
     writer = ...  # type: _writer
-    def __init__(self, f: Any, fieldnames: Sequence[str], restval: Optional[Any], extrasaction: str = ..., dialect: _Dialect = ..., *args: Any, **kwds: Any) -> None: ...
+    def __init__(self, f: Any, fieldnames: Sequence[str],
+                 restval: Optional[Any] = ..., extrasaction: str = ..., dialect: _Dialect = ...,
+                 *args: Any, **kwds: Any) -> None: ...
     def writeheader(self) -> None: ...
     def writerow(self, rowdict: _DictRow) -> None: ...
     def writerows(self, rowdicts: Iterable[_DictRow]) -> None: ...
 
-class Sniffer:
+class Sniffer(object):
     preferred = ...  # type: List[str]
     def __init__(self) -> None: ...
     def sniff(self, sample: str, delimiters: Optional[str] = ...) -> Dialect: ...