diff --git a/duniterpy/constants.py b/duniterpy/constants.py
index 6703e382118363be648ac60bc63bdf81038242cc..1e182dc26afe5fb18f1d18650aacfdda5c287d9b 100644
--- a/duniterpy/constants.py
+++ b/duniterpy/constants.py
@@ -25,8 +25,10 @@ BLOCK_ID_REGEX = "[0-9]+"
 BLOCK_UID_REGEX = "{block_id_regex}-{block_hash_regex}".format(
     block_id_regex=BLOCK_ID_REGEX, block_hash_regex=BLOCK_HASH_REGEX
 )
-CONDITIONS_REGEX = "(&&|\\|\\|| |[()]|(SIG\\({pubkey_regex}\\)|(XHX\\({hash_regex}\\))))*".format(
-    pubkey_regex=PUBKEY_REGEX, hash_regex=HASH_REGEX
+CONDITIONS_REGEX = (
+    "(&&|\\|\\|| |[()]|(SIG\\({pubkey_regex}\\)|(XHX\\({hash_regex}\\))))*".format(
+        pubkey_regex=PUBKEY_REGEX, hash_regex=HASH_REGEX
+    )
 )
 IPV4_REGEX = (
     "(?:(?:[0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.){3}(?:[0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4]["
diff --git a/duniterpy/helpers/blockchain.py b/duniterpy/helpers/blockchain.py
index cc6d433aaa30c96b92a7c0e5f87541dde4a0e790..0e4e10901621e5da1d647f69f4a7815263f70b7e 100644
--- a/duniterpy/helpers/blockchain.py
+++ b/duniterpy/helpers/blockchain.py
@@ -1,3 +1,21 @@
+"""
+Copyright  2014-2020 Vincent Texier <vit@free.fr>
+
+DuniterPy is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+DuniterPy is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""
+
+
 # imports locally stored blockchain in the chunk format
 # example usage :
 # ```
diff --git a/examples/load_local_blockchain.py b/examples/load_local_blockchain.py
index d59ee89118579f6ac4b0ab7a627237487664ef01..0dc9e9ff5693599fd852ed745f3d595a260bd955 100644
--- a/examples/load_local_blockchain.py
+++ b/examples/load_local_blockchain.py
@@ -1,3 +1,21 @@
+"""
+Copyright  2014-2020 Vincent Texier <vit@free.fr>
+
+DuniterPy is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+DuniterPy is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""
+
+
 # this example lets you load locally copy of duniter blockchain into duniterpy objects
 # by default, it searches in ~/.config/duniter/duniter_default/g1/
 
diff --git a/examples/send_identity.py b/examples/send_identity.py
index 1fc29f8980bd947a6e50f7ef0ba0ec42294d0e6d..68bcd4d59069148cf58b9865540a6ab7b3e6ee53 100644
--- a/examples/send_identity.py
+++ b/examples/send_identity.py
@@ -34,7 +34,11 @@ BMAS_ENDPOINT = "BMAS g1-test.duniter.org 443"
 ################################################
 
 
-def get_identity_document(current_block: dict, uid: str, key: SigningKey,) -> Identity:
+def get_identity_document(
+    current_block: dict,
+    uid: str,
+    key: SigningKey,
+) -> Identity:
     """
     Get an Identity document
 
diff --git a/examples/send_membership.py b/examples/send_membership.py
index dfa7139e4ea9c5472ef6ae1cee951310572a7849..acfb79effd4f081dd7b21bb4c31146ddffe063e6 100644
--- a/examples/send_membership.py
+++ b/examples/send_membership.py
@@ -35,7 +35,10 @@ BMAS_ENDPOINT = "BMAS g1-test.duniter.org 443"
 
 
 def get_membership_document(
-    membership_type: str, current_block: dict, identity: dict, key: SigningKey,
+    membership_type: str,
+    current_block: dict,
+    identity: dict,
+    key: SigningKey,
 ) -> Membership:
     """
     Get a Membership document