diff --git a/kheops/plugin/common.py b/kheops/plugin/common.py
index d860468..6d36a1d 100644
--- a/kheops/plugin/common.py
+++ b/kheops/plugin/common.py
@@ -1,49 +1,43 @@
-# from box import Box
-import textwrap
-from pprint import pprint
-import glob
-from pathlib import Path
-from jinja2 import Template
-import yaml
-import json
+"""Common libraries for plugins"""
 
 import logging
+from kheops.utils import schema_validate
 
 log = logging.getLogger(__name__)
 
-from kheops.utils import schema_validate
-import copy
 
 # Candidate Classes
 # =============================
-class Candidate:
-    engine = None
-    found = False
-    data = None
-    run = None
-    scope = None
-    key = None
-
-    def __init__(self, run):
-        self.run = copy.deepcopy(run)
-
-    def __repr__(self):
-        return f"{self.__dict__}"
-
-    def _report_data(self, data=None):
-        default_data = {
-            # "rule": self.config,
-            "value": self.engine._plugin_value,
-            "data": self.data,
-        }
-        data = data or default_data
-        d = json.dumps(data, indent=2)  # , sort_keys=True, )
-        return d
+# class Candidate:
+#     engine = None
+#     found = False
+#     data = None
+#     run = None
+#     scope = None
+#     key = None
+#
+#     def __init__(self, run):
+#         self.run = copy.deepcopy(run)
+#
+#     def __repr__(self):
+#         return f"{self.__dict__}"
+#
+#     def _report_data(self, data=None):
+#         default_data = {
+#             # "rule": self.config,
+#             "value": self.engine._plugin_value,
+#             "data": self.data,
+#         }
+#         data = data or default_data
+#         data = json.dumps(data, indent=2)  # , sort_keys=True, )
+#         return data
 
 
 # Generic Classes
 # =============================
 class PluginClass:
+    """Generic plugin class"""
+
     _plugin_type = "none"
     _plugin_value = None
 
@@ -52,7 +46,6 @@ class PluginClass:
     _schema_props_plugin = {
         "engine": {
             "type": "string",
-            # TODO: Fix this ug
             "default": "jerakia",
         },
         "value": {},
@@ -81,6 +74,8 @@ class PluginClass:
 
 
 class PluginBackendClass(PluginClass):
+    """Backend plugin class"""
+
     _plugin_type = "backend"
 
     def _init(self):
@@ -88,6 +83,8 @@ class PluginBackendClass(PluginClass):
 
 
 class PluginStrategyClass(PluginClass):
+    """Strategy plugin class"""
+
     _plugin_type = "strategy"
 
     def _init(self):
@@ -95,6 +92,8 @@ class PluginStrategyClass(PluginClass):
 
 
 class PluginEngineClass(PluginClass):
+    """Engine plugin class"""
+
     _plugin_type = "engine"
 
     _schema_props_default = {
@@ -132,20 +131,22 @@ class PluginEngineClass(PluginClass):
 
     # Public Methods
     # =====================
-    def dump(self):
+    def dump(self) -> dict:
+        """Dump plugin configuration"""
+
         ret = {
             "config": self.config,
         }
         return ret
 
-    def lookup_candidates(self, key=None, scope=None):
-        raise Exception(f"Module does not implement this method :(")
+    def lookup_candidates(self, key=None, scope=None) -> list:
+        """Placeholder to return candidates"""
+        raise Exception("Module does not implement this method :(")
         # It must always return a list of `Candidate` instances
-        return []
 
-    def _example(self):
-        print(f"Module does not implement this method :(")
-        return None
+    # def _example(self):
+    #     print(f"Module does not implement this method :(")
+    #     return None
 
 
 # File plugins Extensions
@@ -153,6 +154,7 @@ class PluginEngineClass(PluginClass):
 
 
 class PluginFileGlob:
+    """Provide glob functionnality"""
 
     _schema_props_glob = {
         "glob": {