class_docstr: An HC class, inherited from Optimizer.
  
  This is the designed class to define HC-related
  variables and methods.
  
  References:
      S. Skiena. The Algorithm Design Manual (2010).
docstr: Variance of noise distribution.
docstr_tok: ["Variance","of","noise","distribution","."]
code: def r_var(self) -> float:
      """Variance of noise distribution."""
  
      return self._r_var
  
file_path: opytimizer/opytimizer/optimizers/misc/hc.py
imports: from typing import Any, Dict, Optional
  import opytimizer.math.random
  import opytimizer.utils.exception
  from opytimizer.core import Optimizer
  from opytimizer.core.space import Space
  from opytimizer.utils import logging
label_desc: Use image node_id 4 for calling the HC obj's underlying member method code with example usage: obj.r_var() and returns: self