calculate circle area

Author: realDuYuanChao

maths/area.py

@@ -0,0 +1,15 @@
+def circle_area(radius: float) -> float:
+    """
+    >>> circle_area(10)
+    314.1592653589793
+    >>> circle_area(0)
+    0.0
+    """
+    import math
+    return math.pi * radius * radius
+
+
+if __name__ == "__main__":
+    from doctest import testmod
+
+    testmod()