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).
code: def r_var(self, r_var: float) -> None:
      if not isinstance(r_var, (float, int)):
          raise e.TypeError("`r_var` should be a float or integer")
      if r_var < 0:
          raise e.ValueError("`r_var` should be >= 0")
  
      self._r_var = 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 5 for calling the HC obj's underlying member method code with example usage: obj.r_var(r_var) without return types