text: #ifndef _VOLUME_CALCULATOR_H_
  #define _VOLUME_CALCULATOR_H_
  
  #include <map>
  #include <string>
  
  class VolumeCalculator
  {
  public:
    VolumeCalculator(std::map<std::string,std::string> const & args_, std::string const & doc_root_)
      : args(args_)
      , doc_root(doc_root_)
    {}
  
    void calculate(std::string & response);
  
  private:
    std::map<std::string,std::string> args;
    std::string doc_root;
  };
  
  #endif