docs: public static HeadedSyntacticCategory parseFrom(String typeString) {
      // Strip variable numbers and features, without using 
      // regular expressions for GWT compatibility.
      String syntacticString = stripBracketedExpression(typeString, "{", "}");
  
      SyntacticCategory syntax = SyntacticCategory.parseFrom(syntacticString);
      int[] semanticVariables = new int[syntax.getNumSubcategories()];
      parseSemanticVariables(syntax, typeString, semanticVariables, 0);
  
      int rootIndex = syntax.getNumReturnSubcategories();
      return new HeadedSyntacticCategory(syntax, semanticVariables, rootIndex);
    }