What is the first line of code the python interpreter executes?

def sumTo$($aBound$)$:

thesum $=0$

for aNumber in range $(1,$aBound$+1)$ :

thesum $=$ theSum $+$ aNumber

return thesum

print$($sumTo$(4))$

Line $2$

Line $7$

Line $6$

Line $8$

Line $1$