code: void appendOp(int length, int op)
    {
  
      int totalLen = m_ops.getOp(OpMap.MAPINDEX_LENGTH);
  
      m_ops.setOp(totalLen, op);
      m_ops.setOp(totalLen + OpMap.MAPINDEX_LENGTH, length);
      m_ops.setOp(OpMap.MAPINDEX_LENGTH, totalLen + length);
    }
docs: Insert room for operation.  This WILL set
  the length value of the operation, and will update
  the length value for the total expression.
  
  @param length The length of the operation.
  @param op The op code to the inserted.