old_contents: 
  import os
  from conan.packager import ConanMultiPackager
  from conanfile import QuerysetCPP
  
  
  username = os.getenv("CONAN_USERNAME", "jgsogo")
  reference = os.getenv("CONAN_REFERENCE", "{}/{}".format(QuerysetCPP.name, QuerysetCPP.version))
  
  
  if __name__ == "__main__":
      builder = ConanMultiPackager(username=username,
                                   reference=reference,
                                   visual_versions=["14",],
                                   gcc_versions = ["5.4", "6.3",],
                                   apple_clang_versions = ["7.3", "8.1",],
                                   args = "--scope queryset-cpp:BUILD_TEST=1 --build=missing"
                                  )
      builder.add_common_builds(shared_option_name="queryset-cpp:shared")
      filtered_builds = []
      for settings, options, env_vars, build_requires in builder.builds:
          if settings["build_type"] == "Release":
              filtered_builds.append([settings, options, env_vars, build_requires])
      builder.builds = filtered_builds
      print("{} builds ahead!".format(len(builder.builds)))
      builder.run()
  
  
new_contents: 
  import os
  from conan.packager import ConanMultiPackager
  from conanfile import QuerysetCPP
  
  
  username = os.getenv("CONAN_USERNAME", "jgsogo")
  reference = os.getenv("CONAN_REFERENCE", "{}/{}".format(QuerysetCPP.name, QuerysetCPP.version))
  
  
  if __name__ == "__main__":
      builder = ConanMultiPackager(username=username,
                                   reference=reference,
                                   visual_versions=["14",],
                                   args = "--scope queryset-cpp:BUILD_TEST=1 --build=missing"
                                  )
      builder.add_common_builds(shared_option_name="queryset-cpp:shared")
      filtered_builds = []
      for settings, options, env_vars, build_requires in builder.builds:
          if settings["build_type"] == "Release":
              filtered_builds.append([settings, options, env_vars, build_requires])
      builder.builds = filtered_builds
      print("{} builds ahead!".format(len(builder.builds)))
      builder.run()
  
  
subject: use compilers in env variable