docs: final public void Concatenation() throws ParseException {
      Math();
      label_11:
      while (true) {
        switch ((jj_ntk==-1)?jj_ntk():jj_ntk) {
        case CONCAT:
          ;
          break;
        default:
          jj_la1[24] = jj_gen;
          break label_11;
        }
        jj_consume_token(CONCAT);
                      AstConcatenation jjtn001 = new AstConcatenation(JJTCONCATENATION);
                      boolean jjtc001 = true;
                      jjtree.openNodeScope(jjtn001);
        try {
          Math();
        } catch (Throwable jjte001) {
                      if (jjtc001) {
                        jjtree.clearNodeScope(jjtn001);
                        jjtc001 = false;
                      } else {
                        jjtree.popNode();
                      }
                      if (jjte001 instanceof RuntimeException) {
                        {if (true) throw (RuntimeException)jjte001;}
                      }
                      if (jjte001 instanceof ParseException) {
                        {if (true) throw (ParseException)jjte001;}
                      }
                      {if (true) throw (Error)jjte001;}
        } finally {
                      if (jjtc001) {
                        jjtree.closeNodeScope(jjtn001,  2);
                      }
        }
      }
    }