python sum values in list by key code example

Example 1: how to calculate the sum of a list in python

# Python code to demonstrate the working of  
# sum() 
numbers = [1,2,3,4,5,1,4,5] 
  
# start parameter is not provided 
Sum = sum(numbers) 
print(Sum) # result is 25  
# start = 10 
Sum = sum(numbers, 10) 
print(Sum) # result is 10 +25 = 35

Example 2: python add all values of another list

a = [1, 2, 3]
b = [4, 5, 6]
a += b
# another way: a.extend(b)