class_docstr: Represents a DP metric.
  
  Attributes:
      name: the name of the metric, like 'COUNT', 'PERCENTILE'.
      parameter: an optional parameter of the metric, e.g. for 90th
      percentile, parameter = 90.
code: def __repr__(self):
      return self.__str__()
  
imports: import logging
  import math
  from dataclasses import dataclass
  from enum import Enum
  from typing import Any, Sequence, Callable, Optional, List
  import numpy
  from pipeline_dp import input_validators
label_desc: Use image node_id 3 for calling the Metric obj's underlying member method code with example usage: obj.__repr__() and returns: self