code: public HeadedSyntacticCategory getReturnType() {
      SyntacticCategory returnSyntax = syntacticCategory.getReturn();
      int[] returnSemantics = ArrayUtils.copyOf(semanticVariables, rootIndex);
      int returnRoot = returnSyntax.getNumReturnSubcategories();
      return new HeadedSyntacticCategory(returnSyntax, returnSemantics, returnRoot);
    }
docs: Gets the syntactic type and semantic variable assignments to the
  return type of this category.
  
  @return