Return email of user

def get_email(sciper):
    """
    Return email of user
    """
    attribute = 'mail'
    response = LDAP_search(
        pattern_search='(uniqueIdentifier={})'.format(sciper),
        attribute=attribute
    )
    try:
        email = get_attribute(response, attribute)
    except Exception:
        raise EpflLdapException("No email address corresponds to sciper {}".format(sciper))
    return email