Abstract: Systems and techniques for testing machine-readable instructions. In one aspect, a method includes identifying a subroutine in a set of machine-readable instructions that can request a service from a service provider, modifying the identified subroutine to convey a description of a service request to a recorder, and storing the modified subroutine so that the modified subroutine is accessed during subsequent data processing activities and the description of the service request is conveyed to the recorder in response to a request for the service from the service provider during the data processing activities.

Abstract: The wheelchair comprises a seat and two main wheels connected by an axle. A support device, comprising an exchangeable intermediate element consisting of an elastomer element located in the lacuna provided by the spiral turns of a spring, is detachably fixed at one of its end to a chassis of the seat and at its other end to the axle through a center part attached to the middle part of the axle. The center part is arranged to receive the rear ends of the two left and right main frame tubes of the wheelchair.