public Type2Instruction RemoveLast()
        {
            int last = _insts.Count - 1;
            Type2Instruction _lastInst = _insts[last];

            _insts.RemoveAt(last);
            return(_lastInst);
        }
        internal void ChangeFirstInstToGlyphWidthValue()
        {
            //check the first element must be loadint
            Type2Instruction firstInst = _insts[0];

            if (firstInst.Op != OperatorName.LoadInt)
            {
                throw new NotSupportedException();
            }
            //the replace
            _insts[0] = new Type2Instruction(OperatorName.GlyphWidth, firstInst.Value);
        }