class_docstr: Wraps multiple callbacks in an ready-to-use class.
docstr: Performs a list of callbacks whenever a task begins.
  
  Args:
      opt_model: An instance of the optimization model.
docstr_tok: ["Performs","a","list","of","callbacks","whenever","a","task","begins",".","Args",":","opt_model",":","An","instance","of","the","optimization","model","."]
code: def on_task_begin(self, opt_model: Opytimizer) -> None:
      """Performs a list of callbacks whenever a task begins.
  
      Args:
          opt_model: An instance of the optimization model.
  
      """
  
      for callback in self.callbacks:
          callback.on_task_begin(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 4 for calling the CallbackVessel obj's underlying member method code with example usage: obj.on_task_begin(opt_model) without return types