docs: void swapCondition() {
  
          int i = OpTypes.EQUAL;
  
          switch (opType) {
  
              case OpTypes.GREATER_EQUAL :
                  i = OpTypes.SMALLER_EQUAL;
                  break;
  
              case OpTypes.SMALLER_EQUAL :
                  i = OpTypes.GREATER_EQUAL;
                  break;
  
              case OpTypes.SMALLER :
                  i = OpTypes.GREATER;
                  break;
  
              case OpTypes.GREATER :
                  i = OpTypes.SMALLER;
                  break;
  
              case OpTypes.NOT_DISTINCT :
                  i = OpTypes.NOT_DISTINCT;
                  break;
  
              case OpTypes.EQUAL :
                  break;
  
              default :
                  throw Error.runtimeError(ErrorCode.U_S0500,
                                           "Expression.swapCondition");
          }
  
          opType = i;
  
          Expression e = nodes[LEFT];
  
          nodes[LEFT]  = nodes[RIGHT];
          nodes[RIGHT] = e;
      }