docs: def dependency_check(self, task_cls, skip_unresolved=False):
  		""" Check dependency of task for irresolvable conflicts (like task to task mutual dependency)
  
  		:param task_cls: task to check
  		:param skip_unresolved: flag controls this method behaviour for tasks that could not be found. \
  		When False, method will raise an exception if task tag was set in dependency and the related task \
  		wasn't found in registry. When True that unresolvable task will be omitted
  
  		:return: None
  		"""
  
  		def check(check_task_cls, global_dependencies):
  			if check_task_cls.__registry_tag__ in global_dependencies:
  				raise RuntimeError('Recursion dependencies for %s' % task_cls.__registry_tag__)
  
  			dependencies = global_dependencies.copy()
  			dependencies.append(check_task_cls.__registry_tag__)
  
  			for dependency in check_task_cls.__dependency__:
  				dependent_task = self.tasks_by_tag(dependency)
  				if dependent_task is None and skip_unresolved is False:
  					raise RuntimeError(
  						"Task '%s' dependency unresolved (%s)" %
  						(task_cls.__registry_tag__, dependency)
  					)
  
  				if dependent_task is not None:
  					check(dependent_task, dependencies)
  
  		check(task_cls, [])