diff --git a/polyviz/choro.py b/polyviz/choro.py
index 1a5659d..b353156 100644
--- a/polyviz/choro.py
+++ b/polyviz/choro.py
@@ -41,9 +41,7 @@ def choro(
     filepath = check_filepath(filepath, title, "choro", method)
 
     assert isinstance(method, tuple), "`method` should be a tuple."
-    assert isinstance(
-        activity, Activity
-    ), "`activity` should be a Brightway activity."
+    assert isinstance(activity, Activity), "`activity` should be a Brightway activity."
 
     # fetch unit of method
     unit = bw2data.Method(method).metadata["unit"]
diff --git a/polyviz/sankey.py b/polyviz/sankey.py
index 3a5418c..32682e6 100644
--- a/polyviz/sankey.py
+++ b/polyviz/sankey.py
@@ -1,9 +1,8 @@
 """
 This module contains the code to generate a Sankey diagram for a given activity and method.
 """
-from typing import Optional, Tuple
 
-from typing import Union
+from typing import Optional, Tuple, Union
 
 import bw2data
 from d3blocks import D3Blocks
@@ -17,6 +16,7 @@
 except ImportError:
     from bw2data.backends import Activity
 
+
 def sankey(
     activity: Activity,
     method: tuple = None,
diff --git a/polyviz/treemap.py b/polyviz/treemap.py
index 8079d2b..19a0d35 100644
--- a/polyviz/treemap.py
+++ b/polyviz/treemap.py
@@ -41,9 +41,7 @@ def treemap(
     filepath = check_filepath(filepath, title, "treemap", method)
 
     assert isinstance(method, tuple), "`method` should be a tuple."
-    assert isinstance(
-        activity, Activity
-    ), "`activity` should be a brightway2 activity."
+    assert isinstance(activity, Activity), "`activity` should be a brightway2 activity."
 
     # fetch unit of method
     unit = bw2data.Method(method).metadata["unit"]
diff --git a/polyviz/utils.py b/polyviz/utils.py
index 6b0d540..4055473 100644
--- a/polyviz/utils.py
+++ b/polyviz/utils.py
@@ -19,6 +19,7 @@
 except ImportError:
     from bw2data.backends import Activity
 
+
 def calculate_supply_chain(
     activity: Activity,
     method: tuple,
@@ -35,9 +36,7 @@ def calculate_supply_chain(
     :return: a StringIO object and the reference amount
     """
 
-    assert isinstance(
-        activity, Activity
-    ), "`activity` should be a brightway2 activity."
+    assert isinstance(activity, Activity), "`activity` should be a brightway2 activity."
 
     amount = amount * -1 if identify_waste_process(activity) else amount
 
@@ -70,9 +69,7 @@ def calculate_lcia_score(
     :param method: tuple representing a Brightway2 method
     :return: LCIA score, C matrix, and reverse dictionary
     """
-    assert isinstance(
-        activity, Activity
-    ), "`activity` should be a brightway2 activity."
+    assert isinstance(activity, Activity), "`activity` should be a brightway2 activity."
 
     print("Calculating LCIA score...")
 
diff --git a/polyviz/violin.py b/polyviz/violin.py
index 0584765..e430e7d 100644
--- a/polyviz/violin.py
+++ b/polyviz/violin.py
@@ -4,10 +4,10 @@
 
 from typing import Union
 
+import bw2calc
 import bw2data
 import numpy as np
 import pandas as pd
-import bw2calc
 
 try:
     from bw2calc.monte_carlo import MultiMonteCarlo
@@ -46,9 +46,7 @@ def violin(
     assert isinstance(method, tuple), "`method` should be a tuple."
 
     for act in activities:
-        assert isinstance(
-            act, Activity
-        ), "`activity` should be a Brightway activity."
+        assert isinstance(act, Activity), "`activity` should be a Brightway activity."
 
     def make_name(activities):
         """
@@ -73,9 +71,7 @@ def make_name(activities):
         ).calculate()
     else:
         lca = bw2calc.LCA(
-            demand={activities[0]: 1},
-            method=method,
-            use_distributions=True
+            demand={activities[0]: 1}, method=method, use_distributions=True
         )
         lca.lci()
         lca.lcia()