A method for executing computer programs in accordance with a preset priority is provided. The method includes training a classifier to distinguish between machines that are single-user and multi-user based on activity logs of an identified machine. In the enabling step, a changing operation for changing the image forming mode after the trial image forming operation is performed. The dispensing mechanism sprays wiper fluid onto the rotatable dome. The spiral tube is movable along an axial direction of the spiral tube with respect to at least one of the first connecting tube and the second connecting tube. The base plate and the supporting members are secured to a bottom surface of the engaging plate to obtain a workpiece.