diff --git a/README.md b/README.md
index 619ced27..01241cac 100644
--- a/README.md
+++ b/README.md
@@ -7,6 +7,10 @@ Python catalogs of objects providers.
 Example:
 
 ```python
+"""
+Concept example of objects catalogs.
+"""
+
 import objects
 import sqlite3
 
@@ -27,15 +31,15 @@ class Catalog(objects.Catalog):
     Objects catalog.
     """
 
-    database = objects.Singleton(sqlite3.Connection,
+    database = objects.Singleton(provides=sqlite3.Connection,
                                  database='example.db')
     """ :type: (objects.Provider) -> sqlite3.Connection """
 
-    object_a = objects.NewInstance(A,
+    object_a = objects.NewInstance(provides=A,
                                    db=database)
     """ :type: (objects.Provider) -> A """
 
-    object_b = objects.NewInstance(B,
+    object_b = objects.NewInstance(provides=B,
                                    a=object_a,
                                    db=database)
     """ :type: (objects.Provider) -> B """
diff --git a/examples/concept.py b/examples/concept.py
index 5b16c5da..0bfadb7c 100644
--- a/examples/concept.py
+++ b/examples/concept.py
@@ -22,15 +22,15 @@ class Catalog(objects.Catalog):
     Objects catalog.
     """
 
-    database = objects.Singleton(sqlite3.Connection,
+    database = objects.Singleton(provides=sqlite3.Connection,
                                  database='example.db')
     """ :type: (objects.Provider) -> sqlite3.Connection """
 
-    object_a = objects.NewInstance(A,
+    object_a = objects.NewInstance(provides=A,
                                    db=database)
     """ :type: (objects.Provider) -> A """
 
-    object_b = objects.NewInstance(B,
+    object_b = objects.NewInstance(provides=B,
                                    a=object_a,
                                    db=database)
     """ :type: (objects.Provider) -> B """