def __init__(self, package, version):
        """Construct a new requirement.

        :param package: the package name.
        :param version: a semver compatible version specification.
        """
        self.package = package
        self.version = version
        if self.version and not re.match(r"[<=>~]", version[:2]):
            self.version = "=={}".format(self.version)
def _get_selected_path(self):
        """
        Helper function to get the selected path

        @return Gtk.TreePath : returns exactly one path for the selected object
                               or None
        """
        selection = self.get_selection()
        if selection:
            model, selected_paths = self.get_selection().get_selected_rows()
            if selected_paths:
                return selected_paths[0]
        return None