def street_length_total(Gu: nx.MultiGraph) -> float:
    """
    Calculate graph's total street segment length.

    Parameters
    ----------
    Gu
        Undirected input graph.

    Returns
    -------
    length
        Total length (meters) of streets in graph.
    """
    if nx.is_directed(Gu):  # pragma: no cover
        msg = "`Gu` must be undirected."
        raise ValueError(msg)
    return float(sum(d["length"] for u, v, d in Gu.edges(data=True)))

    Calculate graph's total street segment length.

    Parameters
    ----------
    Gu
        Undirected input graph.

    Returns
    -------
    length
        Total length (meters) of streets in graph.
    
osmnx/stats.py