code: def _import_submodules(package_name):
      
      package = sys.modules[package_name]
      out = {}
      for loader, name, is_pkg in pkgutil.walk_packages(package.__path__):
          try:
              #module = importlib.import_module('{}.{}'.format(package_name, name))
              module = importlib.import_module('.{}'.format(name), package=package_name)
              out[name] = module
          except:
              continue
      return out
docs: Import all submodules of a module, recursively
      Adapted from: http://stackoverflow.com/a/25083161
  
      :param package_name: Package name
      :type package_name: str
      :rtype: dict[types.ModuleType]