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

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

Author: pre-commit-ci[bot]

maths/arc_length.py

@@ -1,5 +1,6 @@
 from math import pi
 
+
 def arc_length(angle: float, radius: float) -> float:
     """
     Calculate the arc length of a circle.
@@ -42,6 +43,8 @@ def arc_length(angle: float, radius: float) -> float:
         raise ValueError("angle and radius must be positive")
     return 2 * pi * radius * (angle / 360)
 
+
 if __name__ == "__main__":
     import doctest
+
     doctest.testmod()