Python how to swap two values in one line of code - tuple unpacking

 A common problem we need to solve is how to swap two values

 For example if we have to variables x and y, 

 we might want to swap the

 the values.  

 x = 123

 y = 456

 print('Start values:  a = {} b = {} '.format(x, y))

 temp = x

 x = y

 y = temp

 print('Finish values: a = {} b = {} '.format(x, y))

 A better, more succinct method is to use the cool 'tuple unpacking'

 x = 123

 y = 456

 print('Start values:  a = {} b = {} '.format(x, y))

 x, y = y, x

 print('Finish values: a = {} b = {} '.format(x, y))