From 77db12eaf597e973729c8f34905011f40e48e25d Mon Sep 17 00:00:00 2001
From: MomIsBestFriend <>
Date: Thu, 14 Nov 2019 00:32:54 +0200
Subject: [PATCH 1/3] Typing in pandas/core/dtypes/

---
 pandas/core/dtypes/base.py    | 4 ++--
 pandas/core/dtypes/common.py  | 6 +++---
 pandas/core/dtypes/concat.py  | 2 +-
 pandas/core/dtypes/missing.py | 6 +++---
 4 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/pandas/core/dtypes/base.py b/pandas/core/dtypes/base.py
index d9d3b0d45e218..c90f1cdeaabfd 100644
--- a/pandas/core/dtypes/base.py
+++ b/pandas/core/dtypes/base.py
@@ -86,7 +86,7 @@ def __from_arrow__(
     def __str__(self) -> str:
         return self.name
 
-    def __eq__(self, other):
+    def __eq__(self, other) -> bool:
         """
         Check whether 'other' is equal to self.
 
@@ -119,7 +119,7 @@ def __eq__(self, other):
     def __hash__(self) -> int:
         return hash(tuple(getattr(self, attr) for attr in self._metadata))
 
-    def __ne__(self, other):
+    def __ne__(self, other) -> bool:
         return not self.__eq__(other)
 
     @property
diff --git a/pandas/core/dtypes/common.py b/pandas/core/dtypes/common.py
index 635bc5ce03680..dcc8a274492ee 100644
--- a/pandas/core/dtypes/common.py
+++ b/pandas/core/dtypes/common.py
@@ -726,7 +726,7 @@ def is_string_dtype(arr_or_dtype) -> bool:
     """
 
     # TODO: gh-15585: consider making the checks stricter.
-    def condition(dtype):
+    def condition(dtype) -> bool:
         return dtype.kind in ("O", "S", "U") and not is_period_dtype(dtype)
 
     return _is_dtype(arr_or_dtype, condition)
@@ -1496,7 +1496,7 @@ def is_bool_dtype(arr_or_dtype) -> bool:
     return issubclass(dtype.type, np.bool_)
 
 
-def is_extension_type(arr):
+def is_extension_type(arr) -> bool:
     """
     Check whether an array-like is of a pandas extension class instance.
 
@@ -1561,7 +1561,7 @@ def is_extension_type(arr):
     return False
 
 
-def is_extension_array_dtype(arr_or_dtype):
+def is_extension_array_dtype(arr_or_dtype) -> bool:
     """
     Check if an object is a pandas extension array type.
 
diff --git a/pandas/core/dtypes/concat.py b/pandas/core/dtypes/concat.py
index 768272e173c82..7b3e7d4f42121 100644
--- a/pandas/core/dtypes/concat.py
+++ b/pandas/core/dtypes/concat.py
@@ -88,7 +88,7 @@ def concat_compat(to_concat, axis: int = 0):
 
     # filter empty arrays
     # 1-d dtypes always are included here
-    def is_nonempty(x):
+    def is_nonempty(x) -> bool:
         if x.ndim <= axis:
             return True
         return x.shape[axis] > 0
diff --git a/pandas/core/dtypes/missing.py b/pandas/core/dtypes/missing.py
index df89bd374f22e..34dc7dbc6cb1d 100644
--- a/pandas/core/dtypes/missing.py
+++ b/pandas/core/dtypes/missing.py
@@ -125,7 +125,7 @@ def isna(obj):
 isnull = isna
 
 
-def _isna_new(obj):
+def _isna_new(obj) -> bool:
 
     if is_scalar(obj):
         return libmissing.checknull(obj)
@@ -375,7 +375,7 @@ def notna(obj):
 notnull = notna
 
 
-def _isna_compat(arr, fill_value=np.nan):
+def _isna_compat(arr, fill_value=np.nan) -> bool:
     """
     Parameters
     ----------
@@ -392,7 +392,7 @@ def _isna_compat(arr, fill_value=np.nan):
     return True
 
 
-def array_equivalent(left, right, strict_nan: bool = False):
+def array_equivalent(left, right, strict_nan: bool = False) -> bool:
     """
     True if two arrays, left and right, have equal non-NaN elements, and NaNs
     in corresponding locations.  False otherwise. It is assumed that left and

From 5fc5318f15a2573cc2b8bda05584d2c57bd93fb3 Mon Sep 17 00:00:00 2001
From: MomIsBestFriend <>
Date: Thu, 14 Nov 2019 13:51:40 +0200
Subject: [PATCH 2/3] Fixes to @jbrockmendel review

---
 pandas/core/dtypes/missing.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/dtypes/missing.py b/pandas/core/dtypes/missing.py
index 34dc7dbc6cb1d..aeba4eebc498e 100644
--- a/pandas/core/dtypes/missing.py
+++ b/pandas/core/dtypes/missing.py
@@ -125,7 +125,7 @@ def isna(obj):
 isnull = isna
 
 
-def _isna_new(obj) -> bool:
+def _isna_new(obj):
 
     if is_scalar(obj):
         return libmissing.checknull(obj)

From 6f9941bde9f22159f9f4b11c66fc0020e73a2926 Mon Sep 17 00:00:00 2001
From: MomIsBestFriend <50263213+MomIsBestFriend@users.noreply.github.com>
Date: Thu, 14 Nov 2019 15:25:24 +0200
Subject: [PATCH 3/3] change one thing

Last tests failed because it couldn't reach an URL
---
 pandas/core/dtypes/dtypes.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/dtypes/dtypes.py b/pandas/core/dtypes/dtypes.py
index a0712a0df237b..3d1388db371ca 100644
--- a/pandas/core/dtypes/dtypes.py
+++ b/pandas/core/dtypes/dtypes.py
@@ -51,7 +51,7 @@ def register_extension_dtype(cls: Type[ExtensionDtype]) -> Type[ExtensionDtype]:
 
 class Registry:
     """
-    Registry for dtype inference
+    Registry for dtype inference.
 
     The registry allows one to map a string repr of a extension
     dtype to an extension dtype. The string alias can be used in several