Trying to reverse engineer a List Comprehension so I can understand it

Question

list1 = [1,2,3]

int1 = int(''.join(str(i) for i in list1))

I can't seem to figure out how I'd right this normally.

bitflip · Answer

list1 = [1,2,3]
str1 = ""
for i in list1:
    str1 += str(i)
int1 = int(str1)