Return the volatility of growth.

    Note that, like :func:`pynance.tech.simple.growth` but in contrast to 
    :func:`volatility`, :func:`growth_volatility`
    applies directly to a dataframe like that returned by 
    :func:`pynance.data.retrieve.get`, not necessarily to a single-column dataframe.

    Parameters
    ----------
    eqdata : DataFrame
        Data from which to extract growth volatility. An exception
        will be raised if `eqdata` does not contain a column 'Adj Close'
        or an optional name specified by the `selection` parameter.
    window : int, optional
        Window on which to calculate volatility. Defaults to 20.
    selection : str, optional
        Column of eqdata on which to calculate volatility of growth. Defaults
        to 'Adj Close'
    outputcol : str, optional
        Column to use for output. Defaults to 'Growth Risk'.

    Returns
    ---------
    out : DataFrame
        Dataframe showing the volatility of growth over the specified `window`.

def growth_volatility(eqdata, **kwargs):
    """
    Return the volatility of growth.

    Note that, like :func:`pynance.tech.simple.growth` but in contrast to 
    :func:`volatility`, :func:`growth_volatility`
    applies directly to a dataframe like that returned by 
    :func:`pynance.data.retrieve.get`, not necessarily to a single-column dataframe.

    Parameters
    ----------
    eqdata : DataFrame
        Data from which to extract growth volatility. An exception
        will be raised if `eqdata` does not contain a column 'Adj Close'
        or an optional name specified by the `selection` parameter.
    window : int, optional
        Window on which to calculate volatility. Defaults to 20.
    selection : str, optional
        Column of eqdata on which to calculate volatility of growth. Defaults
        to 'Adj Close'
    outputcol : str, optional
        Column to use for output. Defaults to 'Growth Risk'.

    Returns
    ---------
    out : DataFrame
        Dataframe showing the volatility of growth over the specified `window`.
    """
    _window = kwargs.get('window', 20)
    _selection = kwargs.get('selection', 'Adj Close')
    _outputcol = kwargs.get('outputcol', 'Growth Risk')
    _growthdata = simple.growth(eqdata, selection=_selection)
    return volatility(_growthdata, outputcol=_outputcol, window=_window)