class_docstr: Wraps multiple callbacks in an ready-to-use class.
docstr: Performs a list of callbacks whenever an iteration begins.
  
  Args:
      iteration: Current iteration.
      opt_model: An instance of the optimization model.
docstr_tok: ["Performs","a","list","of","callbacks","whenever","an","iteration","begins",".","Args",":","iteration",":","Current","iteration",".","opt_model",":","An","instance","of","the","optimization","model","."]
code: def on_iteration_begin(
      self, iteration: int, opt_model: Opytimizer
  ) -> None:
      """Performs a list of callbacks whenever an iteration begins.
  
      Args:
          iteration: Current iteration.
          opt_model: An instance of the optimization model.
  
      """
  
      for callback in self.callbacks:
          callback.on_iteration_begin(iteration, opt_model)
  
imports: from typing import List, TypeVar, Union
  import numpy
  import opytimizer.utils.exception
  from opytimizer.core.space import Space
label_desc: Use image node_id 6 for calling the CallbackVessel obj's underlying member method code with example usage: obj.on_iteration_begin(iteration, opt_model) without return types