Added types and typeguard. (#894)

* Added types and typeguard.

Author: gabrieldemarmiesse

Diff for: requirements.txt

@@ -1 +1,2 @@
-tf-nightly
+tf-nightly
+typeguard

Diff for: tensorflow_addons/layers/normalizations.py

@@ -17,6 +17,9 @@
 
 import logging
 import tensorflow as tf
+from typeguard import typechecked
+
+from tensorflow_addons.utils import types
 
 
 @tf.keras.utils.register_keras_serializable(package='Addons')
@@ -67,18 +70,19 @@ class GroupNormalization(tf.keras.layers.Layer):
         - [Group Normalization](https://arxiv.org/abs/1803.08494)
     """
 
+    @typechecked
     def __init__(self,
-                 groups=2,
-                 axis=-1,
-                 epsilon=1e-3,
-                 center=True,
-                 scale=True,
-                 beta_initializer='zeros',
-                 gamma_initializer='ones',
-                 beta_regularizer=None,
-                 gamma_regularizer=None,
-                 beta_constraint=None,
-                 gamma_constraint=None,
+                 groups: int = 2,
+                 axis: int = -1,
+                 epsilon: int = 1e-3,
+                 center: bool = True,
+                 scale: bool = True,
+                 beta_initializer: types.Initializer = 'zeros',
+                 gamma_initializer: types.Initializer = 'ones',
+                 beta_regularizer: types.Regularizer = None,
+                 gamma_regularizer: types.Regularizer = None,
+                 beta_constraint: types.Constraint = None,
+                 gamma_constraint: types.Constraint = None,
                  **kwargs):
         super().__init__(**kwargs)
         self.supports_masking = True

Diff for: tensorflow_addons/utils/BUILD

@@ -9,6 +9,7 @@ py_library(
         "keras_utils.py",
         "test_utils.py",
         "resource_loader.py",
+        "types.py",
     ]),
 )
 

Diff for: tensorflow_addons/utils/types.py

@@ -0,0 +1,21 @@
+# Copyright 2019 The TensorFlow Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Types for typing functions signatures."""
+
+from typing import Union, Callable
+
+Initializer = Union[None, dict, str, Callable]
+Regularizer = Union[None, dict, str, Callable]
+Constraint = Union[None, dict, str, Callable]