docs: @Override
    protected Expression visitVarRefNode(VarRefNode node) {
      Expression translation = variableMappings.maybeGet(node.getName());
      if (translation != null) {
        // Case 1: In-scope local var.
        return translation;
      } else {
        // Case 2: Data reference.
        return genCodeForParamAccess(node.getName(), node.getDefnDecl());
      }
    }