Usage:
focus [ atom-spec ]

Focus adjusts the view and center of rotation based on atoms, bonds, and/or ribbon segments that are displayed (possibly including items that are invisible). If atoms are specified, only those both specified and displayed are considered in making the adjustments. Focusing consists of:

1. adjusting the view to include the item(s) (similar to window)
2. setting the center of rotation to the center of the bounding box of the item(s) (similar to cofr)

See also: center, cofr, set, setcom, window