def install_pip(self, package, save=True, save_dev=False):
        """Installs a pip package.

        :param save: if `True`, pins the package to the Hydrogen requirements
            YAML file.
        :param save_dev: if `True`, pins the package as a development
            dependency to the Hydrogen requirements YAML file.
        :param return: a **single** :class:`Requirement` object, representing
            the installed version of the given package.
        """
        requirement = Requirement.coerce(package)
        click.echo("pip install " + requirement.package)
        cmd = envoy.run("pip install {}".format(str(requirement)))
        if cmd.status_code == 0:
            installed_packages = get_installed_pypackages()
            package = installed_packages[requirement.package]
            requirement.version = "=={}".format(package.version)
            if save:
                self.requirements["all"].add(requirement)
            if save_dev:
                self.requirements["dev"].add(requirement)
            if save or save_dev:
                self.requirements.save()
            return requirement
        else:
            fatal(cmd.std_err)
def __init__(self, root, split="train", transforms=None):
        super().__init__(root=root, transforms=transforms)

        verify_str_arg(split, "split", valid_values=("train", "test"))

        root = Path(root) / "KittiFlow" / (split + "ing")
        images1 = sorted(glob(str(root / "image_2" / "*_10.png")))
        images2 = sorted(glob(str(root / "image_2" / "*_11.png")))

        if not images1 or not images2:
            raise FileNotFoundError(
                "Could not find the Kitti flow images. Please make sure the directory structure is correct."
            )

        for img1, img2 in zip(images1, images2):
            self._image_list += [[img1, img2]]

        if split == "train":
            self._flow_list = sorted(glob(str(root / "flow_occ" / "*_10.png")))