code: def main():
      usage = "usage: %prog [options] <pkg_name>\n\n" + __doc__
      parser = OptionParser(usage=usage)
      opts, args = parser.parse_args()
      if len(args) == 0:
          parser.print_help()
          sys.exit(1)
      mod_name = args[0]
      mods = get_ext_modules(mod_name)
      for mod in mods:
          print("Testing module: " + mod.__name__)
          doctest.testmod(mod, optionflags=doctest.NORMALIZE_WHITESPACE)
  
file_path: dipy/tools/doctest_extmods.py
imports: import sys
  import os
  from os.path import dirname, relpath, sep, join, abspath
  from distutils.sysconfig import get_config_vars
  import doctest
  from optparse import OptionParser
label_desc: Use image node_id 2 for calling a global function with example usage: main() without return types