code: def default_classification_thresholds(classification, unit=None):
      
      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
docs: 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