normalize "in" predicate as disjunction of "=="

[lr4d]

Description:

The following two statements are equivalent:

• x in [1,2,3]
• (x == 1) or (x == 2) or (x == 3)

This approach simplifies the function by just calling itself instead of iterating over a for loop and essentially running the code block under if op == "==": for each value of an "in" predicate

• [ ] Closes #xxxx
• [ ] Changelog entry