def freeze(h, output_yaml, resolve, groups):
    """Output installed packages."""
    if not groups:
        groups = filter(lambda group: not group.lower().startswith("bower"),
                        h.requirements.keys())
    else:
        groups = [text_type.strip(group) for group in groups.split(",")]

    if output_yaml:
        for requirements in h.requirements.values():
            for requirement in requirements:
                if resolve and not requirement.version:
                    requirement.load_installed_version()
        click.echo(h.requirements.yaml)
    else:
        for group in groups:
            if not h.requirements[group]:
                continue
            click.echo("# {}".format(group))
            for requirement in h.requirements[group]:
                if resolve and not requirement.version:
                    requirement.load_installed_version()
                click.echo(str(requirement))
def _storage(self):
        """
        Return the configured django storage backend.
        """
        config = settings.VERIFY_STUDENT["SOFTWARE_SECURE"]

        # Default to the S3 backend for backward compatibility
        storage_class = config.get("STORAGE_CLASS", "storages.backends.s3boto.S3BotoStorage")
        storage_kwargs = config.get("STORAGE_KWARGS", {})

        # Map old settings to the parameters expected by the storage backend
        if "AWS_ACCESS_KEY" in config:
            storage_kwargs["access_key"] = config["AWS_ACCESS_KEY"]
        if "AWS_SECRET_KEY" in config:
            storage_kwargs["secret_key"] = config["AWS_SECRET_KEY"]
        if "S3_BUCKET" in config:
            storage_kwargs["bucket"] = config["S3_BUCKET"]
            storage_kwargs["querystring_expire"] = self.IMAGE_LINK_DURATION

        return get_storage(storage_class, **storage_kwargs)