text: #ifndef STAN_VERSION_HPP
  #define STAN_VERSION_HPP
  
  #include <string>
  
  #ifndef STAN_STRING_EXPAND
  #define STAN_STRING_EXPAND(s) #s
  #endif
  
  #ifndef STAN_STRING
  #define STAN_STRING(s) STAN_STRING_EXPAND(s)
  #endif
  
  #define STAN_MAJOR 2
  #define STAN_MINOR 21
  #define STAN_PATCH 0
  
  namespace stan {
  
  /** Major version number for Stan package. */
  const std::string MAJOR_VERSION = STAN_STRING(STAN_MAJOR);
  
  /** Minor version number for Stan package. */
  const std::string MINOR_VERSION = STAN_STRING(STAN_MINOR);
  
  /** Patch version for Stan package. */
  const std::string PATCH_VERSION = STAN_STRING(STAN_PATCH);
  
  }  // namespace stan
  
  #endif
  