# sum

**sum**(sequence[, start=0])

Sums *start* and the items of a sequence, from left to right, and
returns the total. *start* defaults to `0`

. The items are
normally numbers, and are not allowed to be strings. The fast, correct
way to concatenate sequence of strings is by calling
`''.join(sequence)`

. Note that `sum(range(n), m)`

is equivalent to
`reduce(operator.add, range(n), m)`

. New in version 2.3.