diff --git a/kheops/app.py b/kheops/app.py
index be4c5f5..35ee93f 100644
--- a/kheops/app.py
+++ b/kheops/app.py
@@ -89,7 +89,7 @@ CONF_SCHEMA = {
                                 },
                                 {
                                     "type": "string",
-                                    "description": "Add a path prefix before all paths. This is quite useful to store your YAML data in a dedicated tree.",
+                                    "description": """Add a path prefix before all paths. This is quite useful to store your YAML data in a dedicated tree.""",
                                 },
                             ],
                         },
@@ -149,13 +149,40 @@ CONF_SCHEMA = {
 
 
 class GenericInstance:
+    """
+    GenericInstance class
+
+    :var name: Name of the instace.
+    :vartype name: str or None
+
+    :var run: Json compatible dict for instance runtime data.
+    :vartype run: dict
+
+
+    """
 
     name = None
     run = {}
 
 
 class KheopsNamespace(GenericInstance, QueryProcessor):
+    """
+    Kheops Namespace Class
+
+    """
     def __init__(self, app, name, config=None):
+        """
+        Kheops Namespace Instance
+
+        :param app: Parent Kheops Application. 
+        :type app: Kheops
+
+        :param name: Namespace name. 
+        :type config: str
+
+        :param config: Namespace configuration. 
+        :type config: Any
+        """
 
         self.name = name
         self.config = config or {}
@@ -168,88 +195,19 @@ class KheopsNamespace(GenericInstance, QueryProcessor):
         self.run["path_ns"] = str(Path(app.run["config_src"]).parent.resolve())
 
 
-#    def load_namespace(self, namespace="default"):
-#        # Validate configuration
-#
-#        config = dict(self.raw_config)
-#        try:
-#            config = config[namespace]
-#        except KeyError:
-#            log.error("Can't find namespace '%s' in config '%s'", namespace, config)
-#            sys.exit(1)
-#        config = schema_validate(config, self.schema)
-#
-#        pprint (config)
-#
-#        self.run["path_cwd"]
-#
-#        print ("OKKKKK")
-#
-#
-#        conf2 = config
-#        # Get application paths
-#        path_root = conf2["config"].get("app", {}).get("root", None)
-#        if path_root is None:
-#            path_root = Path(config).parent
-#            log.debug("Root path guessed from conf file location.")
-#        else:
-#            path_root = Path(conf2["config"]["app"]["root"])
-#            log.debug("Root path is steup in config")
-#
-#
-#
-#        path_root = str(path_root.resolve())
-#        self.run["path_root"] = path_root
-#
-#
-#        # path_prefix = conf2["config"]["app"]["prefix"]
-#        # if not path_prefix:
-#        #    path_prefix = ''
-#        # p = Path(path_prefix)
-#        # if not p.is_absolute():
-#        #    p = path_root / p
-#        #    try:
-#        #        p = p.resolve().relative_to(Path.cwd().resolve())
-#        #    except ValueError:
-#        #        pass
-#
-#
-#        # Cache paths
-#        path_cache = Path(conf2["config"]["app"]["cache"])
-#        if not path_cache.is_absolute():
-#            path_cache = Path(path_root) / path_cache
-#        path_cache = str(path_cache)
-#        self.run["path_cache"] = path_cache
-#        self.cache = {
-#                'files': Cache(path_cache),
-#                'queries': Cache(path_cache),
-#                }
-#
-#        # self.run['path_prefix'] = str(p.resolve())
-#        log.debug("Working directory is %s, cwd is: %s", path_root, path_cwd)
-#
-#        return config
-
-
-# def query(self, key=None, scope=None):
-#    processor = QueryProcessor(app=self.app)
-#    result = processor.exec(key, scope)
-#
-#        return result
-
 
 class Kheops(GenericInstance):
-    """Main Kheops Application Instance"""
+    """
+    Kheops Application Class
+
+    """
 
     def __init__(self, config="kheops.yml", namespace="default"):
         """
-        init function
+        Kheops Application Instance
 
-        :param kind: Optional "kind" of ingredients.
-        :type kind: list[str] or None
-        :raise lumache.InvalidKindError: If the kind is invalid.
-        :return: The ingredients list.
-        :rtype: list[str]
+        :param config: Kheops configuration. If it's a string, it loads the config from file path. 
+        :type config: str or dict
         """
 
         # Init
@@ -278,8 +236,7 @@ class Kheops(GenericInstance):
 
         :param config: Kheops configuration, can either be a file path or a dict.
         :type config: dict or str or None
-        :param namespace: Configuration namespace to use.
-        :type namespace: str
+        
         :return: The parsed configuration.
         :rtype: dict
 
@@ -294,7 +251,7 @@ class Kheops(GenericInstance):
             source = "dict"
         return dict_conf
 
-    def lookup2(
+    def lookup(
         self,
         keys=None,
         policy=None,
@@ -302,9 +259,17 @@ class Kheops(GenericInstance):
         trace=False,
         explain=False,
         validate_schema=False,
-        namespace="default",
+        namespace=None,
     ):
-        """Lookup a key in hierarchy"""
+        """
+        Lookup a key in hierarchy
+
+        :param keys: List of keys to query.
+        :type keys: list[str]
+
+        :param scope: Scope key.
+        :type scope: dict
+        """
 
         ret = {}
         # Loop over keys
@@ -314,7 +279,7 @@ class Kheops(GenericInstance):
 
             # Identify namespace and key
             parts = key_def.split(":")
-            ns_name = self.ns_name
+            ns_name = namespace or self.ns_name
             if len(parts) > 1:
                 ns_name = parts[0]
                 key_name = parts[1]
@@ -330,83 +295,92 @@ class Kheops(GenericInstance):
 
             # TODO: This may lead to inconsistant output format :/
             # Return result
-            if len(keys) > 1:
-                log.debug("Append '%s' to results", key_name)
-                ret[key_name] = result
-            else:
-                log.debug("Return '%s' result", key_name)
-                return result
+            #if len(keys) > 1:
+            #    log.debug("Append '%s' to results", key_name)
+            ret[key_name] = result
+            #else:
+            #    log.debug("Return '%s' result", key_name)
+            #    return result
 
         return ret
 
-    def lookup(
-        self,
-        keys=None,
-        policy=None,
-        scope=None,
-        trace=False,
-        explain=False,
-        validate_schema=False,
-    ):
-        """Lookup a key in hierarchy"""
-        log.debug("Lookup key %s with scope: %s", keys, scope)
-        assert isinstance(keys, list), f"Got {keys}"
 
-        query = Query(app=self)
-        ret = {}
-        for key in keys:
-            ret[key] = query.exec(
-                key=key,
-                scope=scope,
-                policy=policy,
-                trace=trace,
-                explain=explain,
-                validate_schema=validate_schema,
-            )
-        return ret
 
-    def dump_schema(self):
-        """Dump configuration schema"""
 
-        ret1 = BackendsManager.get_schema(KheopsPlugins, mode="parts")
-        ret2 = RulesManager.get_schema(KheopsPlugins)
-        print(json.dumps(ret1, indent=2))
-        return
 
-        # ret = self.schema
-        # ret["patternProperties"][".*"]["properties"]["tree"]["items"]["properties"] = ret1
-        # ret["patternProperties"][".*"]["properties"]["tree"]["items"] = ret2
 
-        # print(json.dumps(ret, indent=2))
 
-    def gen_docs(self):
-        """Generate documentation"""
 
-        print("WIP")
-        return None
 
-        # src = {
-        #        "app": {
-        #            "config_schema": None,
-        #            "plugin_managers": {
-        #                    'tree': None,
-        #                    'rules': None,
-        #                }
-        #            }
-        #
-        # r1 = BackendsManager.get_schema(KheopsPlugins, mode='parts')
 
-        # print (json.dumps(r1, indent=2))
+    # def DEPRECATED_lookup(
+    #     self,
+    #     keys=None,
+    #     policy=None,
+    #     scope=None,
+    #     trace=False,
+    #     explain=False,
+    #     validate_schema=False,
+    # ):
+    #     """Lookup a key in hierarchy"""
+    #     log.debug("Lookup key %s with scope: %s", keys, scope)
+    #     assert isinstance(keys, list), f"Got {keys}"
 
-        # ret = {
-        #
-        #    }
+    #     query = Query(app=self)
+    #     ret = {}
+    #     for key in keys:
+    #         ret[key] = query.exec(
+    #             key=key,
+    #             scope=scope,
+    #             policy=policy,
+    #             trace=trace,
+    #             explain=explain,
+    #             validate_schema=validate_schema,
+    #         )
+    #     return ret
 
-        # part_config = r1.get('config_schema', None)
-        # part_item = r1['items']['core_schema']
-        # part_item_plugins = r1['items']['plugin']
+    # def DEPRECATED_dump_schema(self):
+    #     """Dump configuration schema"""
 
-        # for kind, plugins in part_item_plugins.items():
+    #     ret1 = BackendsManager.get_schema(KheopsPlugins, mode="parts")
+    #     ret2 = RulesManager.get_schema(KheopsPlugins)
+    #     print(json.dumps(ret1, indent=2))
+    #     return
 
-        #    for plugin_name, schema in plugins.items():
-        #        part_item_
+    #     # ret = self.schema
+    #     # ret["patternProperties"][".*"]["properties"]["tree"]["items"]["properties"] = ret1
+    #     # ret["patternProperties"][".*"]["properties"]["tree"]["items"] = ret2
+
+    #     # print(json.dumps(ret, indent=2))
+
+    # def DEPRECATED_gen_docs(self):
+    #     """Generate documentation"""
+
+    #     print("WIP")
+    #     return None
+
+    #     # src = {
+    #     #        "app": {
+    #     #            "config_schema": None,
+    #     #            "plugin_managers": {
+    #     #                    'tree': None,
+    #     #                    'rules': None,
+    #     #                }
+    #     #            }
+    #     #
+    #     # r1 = BackendsManager.get_schema(KheopsPlugins, mode='parts')
+
+    #     # print (json.dumps(r1, indent=2))
+
+    #     # ret = {
+    #     #
+    #     #    }
+
+    #     # part_config = r1.get('config_schema', None)
+    #     # part_item = r1['items']['core_schema']
+    #     # part_item_plugins = r1['items']['plugin']
+
+    #     # for kind, plugins in part_item_plugins.items():
+
+    #     #    for plugin_name, schema in plugins.items():
+    #     #        part_item_
diff --git a/kheops/controllers.py b/kheops/controllers.py
index e0dccf7..001cd3b 100644
--- a/kheops/controllers.py
+++ b/kheops/controllers.py
@@ -9,6 +9,8 @@ from prettytable import PrettyTable
 import kheops.plugin as KheopsPlugins
 from kheops.utils import render_template, render_template_python, str_ellipsis
 
+from pprint import pprint
+
 log = logging.getLogger(__name__)
 tracer = logging.getLogger(f"{__name__}.explain")
 
@@ -73,7 +75,7 @@ class QueryProcessor:
     default_match_rule = {
         "key": None,
         "continue": False,
-        "strategy": "merge_deep",
+        "strategy": "merge_schema",
     }
 
     default_lookup_item = {
@@ -100,6 +102,7 @@ class QueryProcessor:
             tracer.setLevel(logging.DEBUG)
 
         query = Query(key, scope)
+        log.info("Creating new query: %s", query.__dict__)
 
         # Match the KeyRule in keys (RULE CACHE)
         # Get the matching keys
@@ -199,11 +202,11 @@ class QueryProcessor:
                 [
                     "\nStatus:" + str_ellipsis(col1, 80),
                     "\nRuntime:" + str_ellipsis(col2, 60),
-                    "\nData:" + str_ellipsis(col3, 60),
+                    "\nKey:" + str_ellipsis(col3, 60),
                 ]
             )
 
-        table.field_names = ["Status", "Runtime", "Data"]
+        table.field_names = ["Status", "Runtime", "Key Value"]
         table.align = "l"
         tracer.info("Explain candidates:\n" + str(table))
 
diff --git a/kheops/plugin/backend/file.py b/kheops/plugin/backend/file.py
index f3b686c..d0bac91 100644
--- a/kheops/plugin/backend/file.py
+++ b/kheops/plugin/backend/file.py
@@ -93,7 +93,7 @@ class Plugin(BackendPlugin):
         status = "not_found"
         for ext, parser in self.extensions.items():
             new_path = os.path.join(self.top_path, path + ext)
-
+            log.debug("Looking into %s", new_path)
             if os.path.isfile(new_path):
                 status = "found"
                 try:
diff --git a/kheops/plugin/common.py b/kheops/plugin/common.py
index 6bacc43..d6ed66c 100644
--- a/kheops/plugin/common.py
+++ b/kheops/plugin/common.py
@@ -112,9 +112,10 @@ class ScopeExtLoop:
     }
 
     def loop_over(
-        self, lookups, conf, var_name="item", callback_context=None, callback=None
+        self, lookups, conf, module_name, var_name="item", callback_context=None, callback=None
     ):
 
+
         var_name = conf.get("var", var_name)
         var_data_ref = conf.get("data", None)
 
@@ -131,7 +132,7 @@ class ScopeExtLoop:
                     var_data = lookup["_run"]["scope"][var_data]
                 except KeyError:
                     log.debug("Ignoring missing '%s' from scope", var_data)
-                    pass
+                    continue
 
             # Run callback
             if callback:
@@ -139,14 +140,14 @@ class ScopeExtLoop:
 
             # Validate generated
             if not isinstance(var_data, list):
-                log.warning("Hier data must be a list, got: %s", var_data)
-                pass
+                log.warning("Loop data must be a list, got: %s", var_data)
+                continue
 
             # Create new object
             for index, var_value in enumerate(var_data):
 
-                if not "hier" in lookup["_run"]:
-                    lookup["_run"]["hier"] = []
+                if not module_name in lookup["_run"]:
+                    lookup["_run"][module_name] = []
 
                 ctx = {
                     "data_ref": var_data_ref,
@@ -157,7 +158,7 @@ class ScopeExtLoop:
 
                 new_item = copy.deepcopy(lookup)
                 new_item["_run"]["scope"][var_name] = var_value
-                new_item["_run"]["hier"].append(ctx)
+                new_item["_run"][module_name].append(ctx)
 
                 ret.append(new_item)
 
diff --git a/kheops/plugin/scope/hier.py b/kheops/plugin/scope/hier.py
index 2df81f4..43d634e 100644
--- a/kheops/plugin/scope/hier.py
+++ b/kheops/plugin/scope/hier.py
@@ -61,6 +61,11 @@ class Plugin(ScopePlugin, ScopeExtLoop):
 
     def _process_item(self, data, ctx):
 
+        # Validate data
+        if not isinstance(data, str):
+            log.debug("Hier data must be a list, got: %s", data)
+            return []
+
         return path_assemble_hier(
             data,
             sep=ctx["var_split"],
@@ -78,6 +83,7 @@ class Plugin(ScopePlugin, ScopeExtLoop):
 
         lookups = self.loop_over(
             lookups,
+            module_name='hier',
             conf=conf,
             var_name="item_hier",
             callback=self._process_item,
diff --git a/kheops/plugin/scope/loop.py b/kheops/plugin/scope/loop.py
index 3d2b80a..2c1153f 100644
--- a/kheops/plugin/scope/loop.py
+++ b/kheops/plugin/scope/loop.py
@@ -63,6 +63,7 @@ class Plugin(ScopePlugin, ScopeExtLoop):
 
         lookups = self.loop_over(
             lookups,
+            module_name='loop',
             conf=conf,
             var_name="item_loop",
         )
diff --git a/kheops/plugin/strategy/__init__.py b/kheops/plugin/strategy/__init__.py
index ceb86f1..339692a 100644
--- a/kheops/plugin/strategy/__init__.py
+++ b/kheops/plugin/strategy/__init__.py
@@ -2,3 +2,4 @@
 
 from . import last
 from . import merge_deep
+from . import merge_schema
diff --git a/kheops/plugin/strategy/merge_deep.py b/kheops/plugin/strategy/merge_deep.py
index 107d2e7..a0c8c19 100644
--- a/kheops/plugin/strategy/merge_deep.py
+++ b/kheops/plugin/strategy/merge_deep.py
@@ -1,4 +1,4 @@
-"""Last strategy Plugin"""
+"""Merge Deep strategy Plugin"""
 
 import logging
 from mergedeep import merge, Strategy
diff --git a/kheops/utils.py b/kheops/utils.py
index 6802efb..788fa8b 100644
--- a/kheops/utils.py
+++ b/kheops/utils.py
@@ -6,6 +6,7 @@ from pathlib import Path
 
 from jinja2 import Template
 from jsonschema import Draft7Validator, validators
+from pprint import pprint
 
 
 log = logging.getLogger(__name__)
@@ -108,7 +109,7 @@ def _extend_with_default(validator_class):
             ):
                 continue
         except Exception as err:
-            print("CATCHED2222 ", err)
+            log.debug("Jsonschema validation error: %s", err)
 
     return validators.extend(
         validator_class,
@@ -124,7 +125,7 @@ def schema_validate(config, schema):
     try:
         DefaultValidatingDraft7Validator(schema).validate(config)
     except Exception as err:
-        print(err)
+        log.error(err)
         path = list(collections.deque(err.schema_path))
         path = "/".join([str(i) for i in path])
         path = f"schema/{path}"