diff --git a/unfold/data_cleaning.py b/unfold/data_cleaning.py
index dcaf62c..c207dc8 100644
--- a/unfold/data_cleaning.py
+++ b/unfold/data_cleaning.py
@@ -409,12 +409,14 @@ def check_commonality_between_databases(original_db, scenario_db, db_name):
             f"and {db_name}."
         )
 
+
 def change_db_name(data, name):
     """
     Originally from `wurst.linking` module.
     Change the database of all datasets in ``data`` to ``name``.
 
-    Raises errors if each dataset does not have exactly one reference production exchange."""
+    Raises errors if each dataset does not have exactly one reference production exchange.
+    """
 
     get_input_databases = lambda data: {ds.get("database") for ds in data}
     old_names = get_input_databases(data)
@@ -423,4 +425,4 @@ def change_db_name(data, name):
         for exc in ds["exchanges"]:
             if exc.get("input") and exc["input"][0] in old_names:
                 exc["input"] = (name, exc["input"][1])
-    return data
\ No newline at end of file
+    return data
diff --git a/unfold/unfold.py b/unfold/unfold.py
index 4b19d5f..819f8c2 100644
--- a/unfold/unfold.py
+++ b/unfold/unfold.py
@@ -21,15 +21,12 @@
 from prettytable import PrettyTable
 from scipy import sparse as nsp
 from wurst import extract_brightway2_databases
-from wurst.linking import (
-    check_duplicate_codes,
-    check_internal_linking,
-    link_internal,
-)
+from wurst.linking import check_duplicate_codes, check_internal_linking, link_internal
 
 from .data_cleaning import (
     add_biosphere_links,
     add_product_field_to_exchanges,
+    change_db_name,
     check_exchanges_input,
     check_for_duplicates,
     correct_fields_format,
@@ -37,7 +34,6 @@
     get_outdated_units,
     remove_categories_for_technosphere_flows,
     remove_missing_fields,
-    change_db_name
 )
 
 try:
@@ -376,11 +372,19 @@ def generate_factors(self) -> None:
 
         """
         self.factors = (
-            self.scenario_df[[
-                c for c in self.scenario_df.columns if c not in [
-                    "to database",
+            self.scenario_df[
+                [
+                    c
+                    for c in self.scenario_df.columns
+                    if c
+                    not in [
+                        "to database",
+                    ]
                 ]
-            ]].groupby("flow id").sum(numeric_only=True).to_dict("index")
+            ]
+            .groupby("flow id")
+            .sum(numeric_only=True)
+            .to_dict("index")
         )
 
     def store_datasets_metadata(self) -> None: