def METHOD_NAME(protocol: str) -> pd.DataFrame:
    """Returns information about historical tvl of a defi protocol.
    [Source: https://docs.llama.fi/api]
    Parameters
    ----------
    protocol: str
        Name of the protocol
    Returns
    -------
    pd.DataFrame
        Historical tvl
    """
    url = f"{API_URL}/protocol/{protocol}"
    r = request(url)
    data = r.json()
    df = pd.DataFrame(data["tvl"])
    df.date = pd.to_datetime(df.date, unit="s")
    df = df.set_index("date")
    return df