#NEWLINE# def __init__( self , key , value , flag = None ) : #NEWLINE# #INDENT# '\n        Represents a base metric. This is not used directly,\n        and is instead invoked from sub-classes that are typed\n        by the metric.\n\n        Each sub-class must implement a class method :meth:`fold()`\n        which takes a list of objects of the same type and returns a list\n        of (key,value,timestamp) pairs.\n\n        :Parameters:\n            - `key` : The key of the metric\n            - `value` : The metric value\n            - `flag` (optional) : An optional metric flag. This is specific\n            to the flag and has no inherint meaning. For example the Counter\n            metric uses this to indicate a sampling rate.\n        ' #NEWLINE# self . key = key #NEWLINE# self . value = value #NEWLINE# self . flag = self