How to check which customers are holding both products in Pandas

I have a dataframe as follows, with many customers and only 2 products (A and B). It is possible for a customer to hold multiple instances of the same product (e.g customer 1 has 4 product A's in the below table). How can I get a list of all customer who hold both products A and B (regardless of quantity)? Thanks.

e.g. the below table should only return customer ID of 1 and 2 since customer 3 only holds product B.

Customer ID	Product
1	A
1	B
1	A
2	A
2	A
1	A
2	B
1	A
3	B
1	A

https://stackoverflow.com/questions/67378635/how-to-check-which-customers-are-holding-both-products-in-pandas May 04, 2021 at 12:01PM