Hello, I wonder why sum does not work on the string sequence in Python 3 : >>> sum((8,5,9,3)) 25 >>> sum([5,8,3,9,2]) 27 >>> sum('rtarze') TypeError: unsupported operand type(s) for +: 'int' and 'str' I naively thought that sum('abc') would expand to 'a'+'b'+'c' And the error message is somewhat cryptic... franck