old_contents: import os
  from ctypeslib.dynamic_module import include
  from ctypes import *
  
  if os.name == "nt":
      _libc = CDLL("msvcrt")
  else:
      _libc = CDLL(None)
  
  include("""\
  #include <stdio.h>
  
  #ifdef _MSC_VER
  #  include <fcntl.h>
  #else
  #  include <sys/fcntl.h>
  #endif
  """,
          persist=False)
  
new_contents: import os
  from ctypeslib.dynamic_module import include
  from ctypes import *
  
  if os.name == "nt":
      _libc = CDLL("msvcrt")
  else:
      _libc = CDLL(None)
  
  _gen_basename = include("""\
  #include <stdio.h>
  
  #ifdef _MSC_VER
  #  include <fcntl.h>
  #else
  #  include <sys/fcntl.h>
  #endif
  
  /* Silly comment */
  """,
          persist=False)
  
subject: Store the basename of the generated files, to allow the unittests to clean up in the tearDown method.