[Closed] Refresh pivot

i`m executing …

selection.pivot = [selection.center.x,selection.center.y,selection.min.z]

Its working fine on objects,but on groups i need to go after to hierarchy-->Pivot-->Affect pivot only ,and hover with my cursor in the viewport, then my pivot is updating , and moving to the script location-min.x.y.z. I didnt find command for refresh pivot-
Is such command existent?
How can i refresh my pivot without doing this step?

thanx