<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def default_classification_thresholds(classification, unit=None):
 """Helper to get default thresholds from classification and unit. :param classification: Classification definition. :type classification: dict :param unit: Unit key definition. :type unit: basestring :returns: Dictionary with key = the class key and value = list of default numeric minimum and maximum value. :rtype: dict """

    thresholds = {}
    for hazard_class in classification['classes']:
        if isinstance(hazard_class['numeric_default_min'], dict):
            min_value = hazard_class['numeric_default_min'][unit]
        else:
            min_value = hazard_class['numeric_default_min']
        if isinstance(hazard_class['numeric_default_max'], dict):
            max_value = hazard_class['numeric_default_max'][unit]
        else:
            max_value = hazard_class['numeric_default_max']
        thresholds[hazard_class['key']] = [min_value, max_value]

    return thresholds