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,
        base,
        filename="",
        data=None,
        ignore_extras=False,
        ignore_installed=False,
        skip_unavailable=False
    ):
        """
        :param base: the dnf base
        :param filename: the filename to load the transaction from (conflicts with the 'data' argument)
        :param data: the dictionary to load the transaction from (conflicts with the 'filename' argument)
        :param ignore_extras: whether to ignore extra package pulled into the transaction
        :param ignore_installed: whether to ignore installed versions of packages
        :param skip_unavailable: whether to skip transaction packages that aren't available
        """

        self._base = base
        self._filename = filename
        self._ignore_installed = ignore_installed
        self._ignore_extras = ignore_extras
        self._skip_unavailable = skip_unavailable

        if not self._base.conf.strict:
            self._skip_unavailable = True

        self._nevra_cache = set()
        self._nevra_reason_cache = {}
        self._warnings = []

        if filename and data:
            raise ValueError(_("Conflicting TransactionReplay arguments have been specified: filename, data"))
        elif filename:
            self._load_from_file(filename)
        else:
            self._load_from_data(data)