diff --git a/Makefile b/Makefile
index 78b043f..9c41b52 100644
--- a/Makefile
+++ b/Makefile
@@ -6,8 +6,11 @@ pytest:
 type:
 	pytype
 
-docs:
+doc:
 	cd docs && make html
 
 spelling:
 	cd docs && make spelling
+
+clean:
+	cd docs && make clean
diff --git a/docs/conf.py b/docs/conf.py
index 624e305..ab7fbbc 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -75,6 +75,7 @@ extensions = [
     'sphinx.ext.mathjax',
     'sphinx.ext.ifconfig',
     'sphinx.ext.viewcode',
+    # 'sphinx.ext.intersphinx',
 ]
 
 if enable_spell_check:
@@ -206,3 +207,10 @@ texinfo_documents = [
 
 
 # -- Extension configuration -------------------------------------------------
+
+# Example configuration for intersphinx: refer to the Python standard library.
+# intersphinx_mapping = {
+#     'python': ('https://docs.python.org/3/', None),
+#     'numpy': ('http://docs.scipy.org/doc/numpy/', None),
+#     'torch': ('http://pytorch.org/docs/master/', None),
+# }
diff --git a/torchy_baselines/common/base_class.py b/torchy_baselines/common/base_class.py
index 6cfdeb2..bbcb951 100644
--- a/torchy_baselines/common/base_class.py
+++ b/torchy_baselines/common/base_class.py
@@ -210,7 +210,10 @@ class BaseRLModel(ABC):
         Checked parameters:
         - observation_space
         - action_space
-        :return: True if environment seems to be coherent
+
+        :param observation_space: (gym.spaces.Space)
+        :param action_space: (gym.spaces.Space)
+        :return: (bool) True if environment seems to be coherent
         """
         if observation_space != env.observation_space:
             return False