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 settings(slug=None):
    slug = slug if slug else "general"

    # get the currently active group
    active_group = SettingsGroup.query.filter_by(key=slug).first_or_404()
    # get all groups - used to build the navigation
    all_groups = SettingsGroup.query.all()

    SettingsForm = Setting.get_form(active_group)

    old_settings = Setting.get_settings(active_group)
    new_settings = {}

    form = SettingsForm()

    if form.validate_on_submit():
        for key, values in iteritems(old_settings):
            try:
                # check if the value has changed
                if values['value'] == form[key].data:
                    continue
                else:
                    new_settings[key] = form[key].data
            except KeyError:
                pass
        Setting.update(settings=new_settings, app=current_app)
        flash(_("Settings saved."), "success")
    else:
        for key, values in iteritems(old_settings):
            try:
                form[key].data = values['value']
            except (KeyError, ValueError):
                pass

    return render_template("management/settings.html", form=form,
                           all_groups=all_groups, active_group=active_group)