def spreadDF(symbol, token='', version=''):
    '''This returns an array of effective spread, eligible volume, and price improvement of a stock, by market.
    Unlike volume-by-venue, this will only return a venue if effective spread is not ‘N/A’. Values are sorted in descending order by effectiveSpread.
    Lower effectiveSpread and higher priceImprovement values are generally considered optimal.

    Effective spread is designed to measure marketable orders executed in relation to the market center’s
    quoted spread and takes into account hidden and midpoint liquidity available at each market center.
    Effective Spread is calculated by using eligible trade prices recorded to the consolidated tape and
    comparing those trade prices to the National Best Bid and Offer (“NBBO”) at the time of the execution.

    View the data disclaimer at the bottom of the stocks app for more information about how these values are calculated.


    https://iexcloud.io/docs/api/#earnings-today
    8am ET M-F

    Args:
        symbol (string); Ticker to request
        token (string); Access token
        version (string); API version

    Returns:
        DataFrame: result
    '''
    df = pd.DataFrame(spread(symbol, token, version))
    _toDatetime(df)
    _reindex(df, 'venue')
    return df
This returns an array of effective spread, eligible volume, and price improvement of a stock, by market.
    Unlike volume-by-venue, this will only return a venue if effective spread is not ‘N/A’. Values are sorted in descending order by effectiveSpread.
    Lower effectiveSpread and higher priceImprovement values are generally considered optimal.

    Effective spread is designed to measure marketable orders executed in relation to the market center’s
    quoted spread and takes into account hidden and midpoint liquidity available at each market center.
    Effective Spread is calculated by using eligible trade prices recorded to the consolidated tape and
    comparing those trade prices to the National Best Bid and Offer (“NBBO”) at the time of the execution.

    View the data disclaimer at the bottom of the stocks app for more information about how these values are calculated.


    https://iexcloud.io/docs/api/#earnings-today
    8am ET M-F

    Args:
        symbol (string); Ticker to request
        token (string); Access token
        version (string); API version

    Returns:
        DataFrame: result