Calculates the temperature equivalent from a series of average daily temperatures
    according to the formula: 0.6 * tempDay0 + 0.3 * tempDay-1 + 0.1 * tempDay-2

    Parameters
    ----------
    series : Pandas Series

    Returns
    -------
    Pandas Series

def calculate_temperature_equivalent(temperatures):
    """
    Calculates the temperature equivalent from a series of average daily temperatures
    according to the formula: 0.6 * tempDay0 + 0.3 * tempDay-1 + 0.1 * tempDay-2

    Parameters
    ----------
    series : Pandas Series

    Returns
    -------
    Pandas Series
    """

    ret = 0.6*temperatures + 0.3*temperatures.shift(1) + 0.1*temperatures.shift(2)
    ret.name = 'temp_equivalent'
    return ret