Representation of the values to use for a module instance's parameters (not ports).
This is a tagged union type, introduced by deftagsum.
There are two kinds of argument lists for the parameters of module instantiations, which we call plain and named arguments.
myalu #(3, 6) alu1 (...); <-- "plain" arguments myalu #(.size(3), .delay(6)) alu2 (...); <-- "named" arguments
A