message: C++17 is now required
diff: -cmake_minimum_required (VERSION 3.5)
  +cmake_minimum_required (VERSION 3.9.4)
  project (DataFrame VERSION 1.0.0)
  set(CMAKE_EXPORT_COMPILE_COMMANDS ON) # Produce compile_commands.json
  -set(CMAKE_CXX_STANDARD 14)
  +set(CMAKE_CXX_STANDARD 17)
  set(CMAKE_CXX_STANDARD_REQUIRED ON)
  set(CMAKE_POSITION_INDEPENDENT_CODE ON)
  