I'm trying to use the 'RDKit Highlighting Atoms' node to show MCSS among a series of compounds. The node seems to require a column containing a collection of atom numbers. How do I extract these atom numbers from a substructure? The only description I found in the forums is to use it with the 'Substructure Filter' node. However, this only takes in SMARTS queries. There's two additional challenges with this: 1) SMARTS doesn't seem to be a format supported by the OpenBabel conversion tool (my compounds are in SMILES format), and 2) the 'RDKit Substructure Filter' node only allows hard-coded SMARTS queries (I can't change it dynamically with a Flow Variable).