def METHOD_NAME(
    num_days_behind: int = 5,
    start_date: Optional[str] = None,
) -> pd.DataFrame:
    """Past IPOs dates. [Source: Finnhub]
    Parameters
    ----------
    num_days_behind: int
        Number of days to look behind for IPOs dates
    start_date: str
        The starting date (format YYYY-MM-DD) to look for IPOs
    Returns
    -------
    pd.DataFrame
        Get dataframe with past IPOs
    """
    today = datetime.now()
    start = (
        (today - timedelta(days=num_days_behind)).strftime("%Y-%m-%d")
        if start_date is None
        else start_date
    )
    df_past_ipo = (
        get_ipo_calendar(start, today.strftime("%Y-%m-%d"))
        .rename(columns={"Date": "Past"})
        .fillna("")
    )
    if df_past_ipo.empty:
        console.print(f"No IPOs found since the last {num_days_behind} days")
    else:
        df_past_ipo = df_past_ipo.sort_values("Past", ascending=False)
    return df_past_ipo