def square(x):
   return x*x

print square(3)

def modifylist(x,y):
   x[0] = y

q = [1,2,3]
print q[0]
modifylist(q,5)
print q[0]

def nomodify(r):
    r = 1

s = 5
print s
nomodify(s)
print s

joe = square
print joe(3)