docs: public static SymbolToken symbol(final String name, final int val)
      {
          if (name == null) { throw new NullPointerException(); }
          if (val <= 0) { throw new IllegalArgumentException("Symbol value must be positive: " + val); }
  
          return new SymbolToken()
          {
              public String getText()
              {
                  return name;
              }
  
              public String assumeText()
              {
                  return name;
              }
  
              public int getSid()
              {
                  return val;
              }
  
              @Override
              public String toString()
              {
                  return "(symbol '" + getText() + "' " + getSid() + ")";
              }
          };
      }