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 _rename_item_names(self, start_index):
    for index, item in enumerate(self._items[start_index:]):
      item.label.set_label(self._get_item_name(index + 1 + start_index))