code: def build_from_c_and_cpp_files(extensions):
      
      for extension in extensions:
          sources = []
          for sfile in extension.sources:
              path, ext = os.path.splitext(sfile)
              if ext in ('.pyx', '.py'):
                  if extension.language == 'c++':
                      ext = '.cpp'
                  else:
                      ext = '.c'
                  sfile = path + ext
              sources.append(sfile)
          extension.sources = sources
docs: Modify the extensions to build from the .c and .cpp files.
      This is useful for releases, this way cython is not required to
      run python setup.py install.