Why is “1000000000000000 in range(1000000000000001)” so fast in Python 3?

Question

It is my understanding that the range() function, which is actually an object type in Python 3, generates its contents on the fly, similar to a generator.

Answer 1

TLDR; range is an arithmetic series so it can very easily calculate whether the object is there.It could even get the index of it if it were list like really quickly.