text: #ifndef PROTEAN_VARIANT_ERROR_HPP
  #define PROTEAN_VARIANT_ERROR_HPP
  
  #include <protean/config.hpp>
  
  #include <boost/throw_exception.hpp>
  #include <boost/format.hpp>
  #include <boost/utility.hpp>
  #include <stdexcept>
  #include <sstream>
  
  namespace protean {
  
      class variant_error : public std::runtime_error
      {
      public:
          variant_error(const std::string& what_arg) :
              std::runtime_error(what_arg.c_str())
          {}
      };
  
  } // namespace protean
  
  #endif // PROTEAN_VARIANT_ERROR_HPP
  