Sets the plugin directories to `directories`. This will delete
        the previous state stored in `self.plugin_directories` in favor
        of the `directories` passed in.

        `directories` may be either a single object or an iterable.

        `directories` can contain relative paths but will be
        converted into absolute paths based on the current working
        directory.

        if `except_blacklisted` is `True` all `directories` in
        `self.blacklisted_directories` will be removed

def set_directories(self, directories, except_blacklisted=True):
        """
        Sets the plugin directories to `directories`. This will delete
        the previous state stored in `self.plugin_directories` in favor
        of the `directories` passed in.

        `directories` may be either a single object or an iterable.

        `directories` can contain relative paths but will be
        converted into absolute paths based on the current working
        directory.

        if `except_blacklisted` is `True` all `directories` in
        `self.blacklisted_directories` will be removed
        """
        directories = util.to_absolute_paths(directories)
        if except_blacklisted:
            directories = self._remove_blacklisted(directories)

        self.plugin_directories = directories