pyuser@deyu:~/zzz$ cat function2.py
#!/usr/bin/python
def add( x1, x2 ):
result = x1 +x2
print(result)
return
a = int(input("a = "))
b = int(input("b = "))
print("a + b =", end=' ')
add(a,b)
pyuser@deyu:~/zzz$ ./function2.py a = 13 b = 2 a + b = 15