Python sum function

The function prototype

sum(iterable[, start])

Function description

sum Function is mainly used to calculate the sum of an iteratable sequence . In special circumstances ,sum Function can also be used to connect two lists .

The usage function

1、 Calculate the sum of the sequence

>>> idx_list = [1, 2, 3, 4]
>>> sum(idx_list)
10
>>> sum(idx_list, start=2)
12

2、 Connect two sequences

>>> idx_list = [[1, 2, 3], [4, 5, 6]]
>>> sum(idx_list, [])
[1, 2, 3, 4, 5, 6]