text: ///////////////////////////////////////////////////////////////////////////////
  //  Copyright Christopher Kormanyos 2017 - 2018.
  //  Distributed under the Boost Software License,
  //  Version 1.0. (See accompanying file LICENSE_1_0.txt
  //  or copy at http://www.boost.org/LICENSE_1_0.txt)
  //
  
  // chapter03_15-002_digit_separators.cpp
  
  #include <iostream>
  
  constexpr long double pi =
    3.1415926535'8979323846'2643383279'5028841972L;
  
  int main()
  {
    std::cout << "pi is " << pi << std::endl;
  }
  