How do I convert a list of ascii values to a string in python?

You are probably looking for 'chr()':

>>> L = [104, 101, 108, 108, 111, 44, 32, 119, 111, 114, 108, 100]
>>> ''.join(chr(i) for i in L)
'hello, world'

Same basic solution as others, but I personally prefer to use map instead of the list comprehension:

>>> L = [104, 101, 108, 108, 111, 44, 32, 119, 111, 114, 108, 100]
>>> ''.join(map(chr,L))
'hello, world'