Write function heron which calculates the area of a triangle with sides a, b, and c.
Heron's formula: sqrt (s \* (s - a) \* (s - b) \* (s - c)), where s = (a + b + c) / 2.
Output should have 2 digits precision.
heron=lambda*args:(lambda a,b,c,s:round((s*(s-a)*(s-b)*(s-c))**.5,2))(*args,sum(args)/2)
heron=lambda*args:(lambda a,b,c,s:round((s*(s-a)*(s-b)*(s-c))**.5,2))(*args,sum(args)/2)