Each instance should have two '->' properties: np1_ and np2_. These should be set to the match sub-tree for the first and second elements of the noun list (respectively). Note that we assume there are only two elements in each list grammar item - this isn't because we want to limit noun lists to two elements, but rather because we assume that the grammars for longer lists will be constructed recursively out of two-element nodes: A, B, C, D becomes something along the lines of List(a, List(b, List(c, List(d)))).

class NounListProduction :   Production