def rolling_std(df, window, shift=1):
    """Calculate rolling std of all numeric columns of a pandas dataframe

    Function can be used by ApplyFunc module.

    :param pd.DataFrame df: input pandas dataframe
    :param int shift: size of shift. default is 1.
    :param int window: size of rolling window.
    :return: df with rolling std of columns
    """
    return df.shift(shift).rolling(window).std()
