def build_url(url, store_name, key):
    """This method combine the different parts of the urls to build the url to
    acces the REST-API.

    Parameters
    ----------
    url : str
        the base url
    store_name : str
        the name of the voldemort store
    key : str
        the url part which represents the key or keys

    Returns
    -------
    str
        the combined url of the REST-API
    """
    return "%s/%s/%s" % (url, store_name, key)