Use of MaterialFunctionAssignment object?

Hello,
how can I use the Functions values returned by the FamilyType.CompundStructureLayers node?

I need to screen a list of materials by function…

Also, where are all this data types described? is there a Reference guide with all nodes that work with specific data types in dynamo? This is the single most time consuming task in dynamo: to figure out what data type can be used in which node…

thank you