Let’s start from the middle of this expression. '3' * 2 evaluates to '33'. This is because multiplication of a str object by a int object results in concatenating string with itself n times (providing you are multiplying by n).
int('33') is just 33 as an integer. When you feed int class a string it will try to convert it to a number, and will raise ValueError if it cannot convert (like int('xfew')). int has an optional second argument base, that specifies the numeric base in with string is written. For instance int('ff', 16) returns 255. base is by default equal to 10.
Operator // is an operator of integer division. Therefore 33 // 11 is equal to 3. Note that 33 / 11 is equal to 3.0, a float. Of course after converting it to int this will also be just 3.
int(3) does really nothing. Just returns 3. Concluding spam[int(int('3' * 2) // 11)] evals to spam[3]:
spam = ['a', 'b', 'c', 'd']
spam[int(int('3' * 2) // 11)] # returns 'd'
solved List question from the boot automating the boring stuff [closed]