Resize: Changes the intended size for the managed instance group. If you increase the size, the group schedules actions to create new instances using the current instance template. If you decrease the size, the group schedules delete actions on one or more instances. The resize operation is marked DONE when the resize actions are scheduled even if the group has not yet added or deleted any instances. You must separately verify the status of the creating or deleting actions with the listmanagedinstances method.