Search the difference: Why this function defenition does'nt work?

[husam]

hi, I'm a beginner to python and try to understand some basic stuff. 
Hier are two function defenitions , which look the same for me, but the 
second one does not work. Can anybody explain why?

def fun1 (*args):
	sum=args[0]
	for next in args[1:]
		sum=sum+next
	return sum
print fun1('a','b','c')
 >>>abc


def fun2 (*args):
	sum=args[:0]
	for next in args[1:]
		sum=sum+next
	return sum

print fun2('a','b','c')

 >>> TypeError: illegal argument type for built-in operation


Thanks in advance.

PS: the first code is taken from Learning Python by Lutz & Ascher. The 
second one is the one I made to solve a small educational problem.