function to find active (not marked as finished) iterations 

		Returns
		-------
			list: all active iteration objects (empty if there are none)

def active_iterations(self):
		"""
		function to find active (not marked as finished) iterations 

		Returns
		-------
			list: all active iteration objects (empty if there are none)
		"""

		l = list(filter(lambda idx: not self.iterations[idx].is_finished, range(len(self.iterations))))
		return(l)