<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _calculate_degree_days(temperature_equivalent, base_temperature, cooling=False):
 """ Calculates degree days, starting with a series of temperature equivalent values Parameters temperature_equivalent : Pandas Series base_temperature : float cooling : bool Set True if you want cooling degree days instead of heating degree days Returns ------- Pandas Series called HDD_base_temperature for heating degree days or CDD_base_temperature for cooling degree days. """


    if cooling:
        ret = temperature_equivalent - base_temperature
    else:
        ret = base_temperature - temperature_equivalent

    # degree days cannot be negative
    ret[ret < 0] = 0

    prefix = 'CDD' if cooling else 'HDD'
    ret.name = '{}_{}'.format(prefix, base_temperature)

    return ret