In [1]:
print('hello world')


hello world

In [7]:
from math import pi
def circumference(r):
    return pi * 2 * r

circumference(1)


Out[7]:
6.283185307179586

In [8]:
def surface(r):
    return pi * r ** 2
surface(1)


Out[8]:
3.141592653589793

In [ ]: