[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Author: pre-commit-ci[bot]

examples/hotelling_law/tests.py

@@ -32,9 +32,9 @@ def test_decreasing_price_variance():
 
     df_model = model.datacollector.get_model_vars_dataframe()
 
-    assert check_slope(
-        df_model["Price Variance"], increasing=False
-    ), "The price variance should decrease over time."
+    assert check_slope(df_model["Price Variance"], increasing=False), (
+        "The price variance should decrease over time."
+    )
 
 
 def test_constant_price_variance():
@@ -53,6 +53,6 @@ def test_constant_price_variance():
 
     df_model = model.datacollector.get_model_vars_dataframe()
 
-    assert (
-        get_slope(df_model["Price Variance"]) == 0
-    ), "The price variance constant over time."
+    assert get_slope(df_model["Price Variance"]) == 0, (
+        "The price variance constant over time."
+    )