diff --git a/mia_core/models.py b/mia_core/models.py
index c1a0a3c..df557b6 100644
--- a/mia_core/models.py
+++ b/mia_core/models.py
@@ -79,7 +79,8 @@ class User(models.Model):
     visits = models.PositiveSmallIntegerField(null=True)
     visited_at = models.DateTimeField(null=True, db_column="visited")
     visited_ip = models.GenericIPAddressField(null=True, db_column="ip")
-    visited_host = models.CharField(max_length=128, null=True, db_column="host")
+    visited_host = models.CharField(
+        max_length=128, null=True, db_column="host")
     visited_country = models.ForeignKey(
         Country, on_delete=models.PROTECT, null=True,
         db_column="ct", to_field="code", related_name="users")
diff --git a/mia_core/period.py b/mia_core/period.py
index 9f97001..2c25115 100644
--- a/mia_core/period.py
+++ b/mia_core/period.py
@@ -81,8 +81,7 @@ class Period:
     _data_start = None
     _data_end = None
 
-    def __init__(
-            self, spec = None, data_start = None, data_end = None):
+    def __init__(self, spec=None, data_start=None, data_end=None):
         self._period = self.Parser(spec)
         self._data_start = data_start
         self._data_end = data_end
diff --git a/mia_core/utils.py b/mia_core/utils.py
index ac795d6..0ae0293 100644
--- a/mia_core/utils.py
+++ b/mia_core/utils.py
@@ -63,7 +63,7 @@ class Language:
 
 def get_multi_language_attr(model, name):
     """Returns a multi-language attribute of a data model.
-    
+
     Args:
         model (object): The data model.
         name (str): The attribute name.
@@ -466,6 +466,7 @@ class SqlQuery:
     """
     sql = ""
     params = []
+
     def __init__(self, sql, params):
         self.sql = sql
         self.params = params