Can someone explain to me the following expression:

variable1=()
variable2=0
......adding nubers in that tuple... and then
for x in (variable1):
variable2=variable2+x

where we basically add all the numbers in that tuple.
What allows us to formulate for... expression in this way and how do we explain it in detail?

Question

Can someone explain to me the following expression:

variable1=()
variable2=0
......adding nubers in that tuple... and then
for x in (variable1):
        variable2=variable2+x

where we basically add all the numbers in that tuple. 
What allows us to  formulate for... expression in this way and how do we explain it in detail?

anonymous · Answer

the last line of the code coud be like "variable2 += x", and you don't really need those parens around variable1 in for.. statement.

anonymous · Answer

I don't need the parents because I have already appointed variable1 as a name for the tuple is that correct?

anonymous · Answer

http://dpaste.com/709256/

anonymous · Answer

yes, you've already set vaalue of variable1 as tuple. The for.. loop iterates over each element in that tuple, and on each iteration (step) of this loop, value of the next element of tuple is assigned to x, which is then added to variable2