You are working on the pgmpy/pgmpy repository. The source code is checked out at /testbed at commit…

You are working on the pgmpy/pgmpy repository. The source code is checked out at /testbed at commit…: a task in SWE-Lego-RL-2699 (Harbor dataset). Describe the solution you'd like - Generalize the implementation of GraphRolesMixin to allow variables to have multiple roles. - Update the test cases…

The task

**Describe the solution you'd like** - Generalize the implementation of `_GraphRolesMixin` to allow variables to have multiple roles. - Update the test cases to also test multiple roles.

Part of Lego-X/Lego-RL-2699.