Production definition names appear in uses in TModel

[toinehartman]

Describe the bug

Production definition names appear in uses in TModel.

To Reproduce

void production() {
    println("===== Productions ====");
    tm = typeCheck(
        "lexical L = \"l\";
        'syntax S = L+;");

    defs = {<d, role> | Define _:<_, _, _, role, d, _> <- tm.defines, role in syntaxRoles};
    print("Defs with roles: ");
    iprintln(defs);

    uses = tm.useDef o defs;
    // A use exists at the location of every definition name
    print("Uses: ");
    iprintln(uses);
    println("======================\n");
}

Expected behavior Not to have definition names in uses.