def get_dir_from_zipfile(zip_file, fallback=None):
    """Return the name of the root folder in a zip file.

    :param zip_file: a :class:`zipfile.ZipFile` instance.
    :param fallback: if `None`, the name of the zip file is used. This is
        returned if the zip file contains more than one top-level directory,
        or none at all.
    """
    fallback = fallback or zip_file.filename
    directories = [name for name in zip_file.namelist() if name.endswith("/")
                   and len(PurePath(name).parts) == 1]
    return fallback if len(directories) > 1 else directories[0]
def render(self, context):
        try:
            if self.params:
                params = template.Variable(self.params).resolve(context)
            else:
                params = {}

            # try matching an address string literal
            email_literal = self.email.strip().lower()
            if EMAIL_RE.match(email_literal):
                email = email_literal
            # treat as a variable
            else:
                email = template.Variable(self.email).resolve(context)
        except template.VariableDoesNotExist:
            return ''

        # now, we generate the gravatar url
        return _build_gravatar_url(email, params)