text: #pragma once
  
  #include "common_data.hpp"
  
  class common_header : public common_data
  {
  public:
      common_header() {};
      virtual size_t      get_length() = 0;
      virtual void        set_payload_length(size_t) = 0;
      virtual size_t      get_payload_length() = 0;
      virtual const char *get_bytestring() = 0;
      virtual size_t      set(const std::string &) = 0;
      virtual ~common_header() {};
  };
  