text: #ifndef Circumference_hpp
  #define Circumference_hpp
  
  #include <shapes/Circle.hpp>
  #include <shapes/Rectangle.hpp>
  
  #include <boost/math/constants/constants.hpp>
  namespace bmc = boost::math::constants;
  
  float
  circumference( Rectangle const & r )
  {
    return 2 * r.width + 2 * r.height;
  }
  
  float
  circumference( Circle const & c )
  {
    return 2 * bmc::pi<float>() * c.radius;
  }
  
  #endif // Circumference_hpp
  