improve upon stylistic choice of Mul function

The function seemed too crammed to me, so I made it look much more
spacious than before.

Signed-off-by: IO-23 Oleh Shmuliar <hasslesstech@tutanota.com>

calculator.cpp

@@ -10,7 +10,11 @@ int Calculator::Sub (double a, double b)
     return Add (a, -b);
 }
 
-int Calculator::Mul (double a, double b)
+int
+Calculator::Mul(double  a,
+                double  b)
 {
-    return a * b + 0.5;
+    return a
+         * b
+         + 0.5;
 }