code: def __repr__(self) -> str:
      def _add_spaces(str_, n_spaces=4):
          return "\n".join(
              [(" " * n_spaces) + line for line in str_.split("\n")]
          )
  
      main_str = "\n".join(
          [
              f"{name}: {repr(meter)}"
              for name, meter in self._meters.items()
          ]
      )
      child_str = "\n".join(
          [
              f"{name}:\n{_add_spaces(repr(meterdict))}"
              for name, meterdict in self._meterdicts.items()
          ]
      )
      if child_str:
          main_str = "\n".join([main_str, child_str])
      return main_str
  
imports: from __future__ import annotations
  import warnings
  import json
  from typing import Dict, Union, Optional
  from collections import OrderedDict
  from .meters import Meter
label_desc: Use image node_id 18 for calling the MeterDict obj's underlying member method code with example usage: obj.__repr__() and returns: main_str, str