code: def get_mean(self) -> float:
      raise NotImplementedError()
  
imports: from abc import ABC
  from typing import Dict, Optional
  import numpy
  from .None import Indicator
  from ...util.values import to_numpy
label_desc: Use image node_id 1 for calling the NumericIndicator obj's underlying member method code with example usage: obj.get_mean() without return types