#!/usr/bin/python3
a=10
b=20
#def add3(a,b):
 #   ''' function calc an addition'''
  #  return(a + b)
#print(add3(a,b))

#moy = add3(a,b)
#print(moy / 2)

#bonne manière
a=10
b=20
def add3(a,b):
    ''' function calc an addition'''
    return((a + b)/2)
print(add3(a,b))
