text: /*
  * File: variable.h
  * Author: Kolger Hajati
  * Date: May 7, 2019
  * Purpose: The file stores variables of node tree.
  */
  
  class Variable: public Operand
  {
  public:
      Variable(string name)
      {
          this->name = name;
      }
      int evaluate();
  private:
      string name;
  };
  