code: @Override
      public void sawOpcode(int seen) {
          try {
              stack.precomputation(this);
  
              if (seen == Const.INVOKEVIRTUAL) {
                  checkForTailRecursion();
              }
          } finally {
              stack.sawOpcode(this, seen);
          }
      }
docs: implements the visitor to find methods that employ tail recursion
  
  @param seen
  the opcode of the currently parsed instruction